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University of Johannesburg
1.
Nhlapo, Thabiso J.
Gain equalization of erbium doped fibre amplifiers with tuneable long-period gratings.
Degree: 2009, University of Johannesburg
URL: http://hdl.handle.net/10210/2176 
► M.Ing.
This thesis is about the gain equalization of erbium doped fibre amplifiers (EDFA), which is a key technology for enabling wavelength-division multiplexed (WDM) optical…
(more)
▼ M.Ing.
This thesis is about the gain equalization of erbium doped fibre amplifiers (EDFA), which is a key technology for enabling wavelength-division multiplexed (WDM) optical communication systems. In order to flatten dynamically the EDFA gain spectrum, a tuneable long-period grating filter was demonstrated. Long-period gratings were fabricated by using a KrF excimer laser combined with the metal amplitude mask technique. The transmission spectrum characteristic of the long- period grating was simulated theoretically by the coupled-mode theory. The coupling between the core and cladding modes of the long-period grating was investigated both experimentally and theoretically. The EDFA was constructed by using the forward pumping configuration consisting of pump laser source, WDM couplers, an optical isolator, and the erbium-doped fibre. The EDFA was characterized theoretically and experimentally for WDM applications. The tuneable long-period grating filter design is based on the tuneable coupler that uses the Mach-Zehnder interferometer configuration. The tuneable filter was demonstrated by equalizing the EDFA gain spectrum and the amplified spontaneous emission (ASE) source. The main advantage of this filter compared to other optical filters is its tuneability of the attenuation over a wide range of pump power.
Subjects/Keywords: Optical amplifiers; Optical fibers; Optical communications
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APA (6th Edition):
Nhlapo, T. J. (2009). Gain equalization of erbium doped fibre amplifiers with tuneable long-period gratings. (Thesis). University of Johannesburg. Retrieved from http://hdl.handle.net/10210/2176
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Nhlapo, Thabiso J. “Gain equalization of erbium doped fibre amplifiers with tuneable long-period gratings.” 2009. Thesis, University of Johannesburg. Accessed February 27, 2021.
http://hdl.handle.net/10210/2176.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Nhlapo, Thabiso J. “Gain equalization of erbium doped fibre amplifiers with tuneable long-period gratings.” 2009. Web. 27 Feb 2021.
Vancouver:
Nhlapo TJ. Gain equalization of erbium doped fibre amplifiers with tuneable long-period gratings. [Internet] [Thesis]. University of Johannesburg; 2009. [cited 2021 Feb 27].
Available from: http://hdl.handle.net/10210/2176.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Nhlapo TJ. Gain equalization of erbium doped fibre amplifiers with tuneable long-period gratings. [Thesis]. University of Johannesburg; 2009. Available from: http://hdl.handle.net/10210/2176
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Johannesburg
2.
Botha, Roelene.
Towards an integrated optic tuneable gain equalizer for erbium-doped fibre amplifiers.
Degree: 2009, University of Johannesburg
URL: http://hdl.handle.net/10210/2153
► M.Ing.
Long distance optical communication systems experience a large degree of attenuation due to fibre losses, necessitating signal amplification. Erbium Doped Fibre Amplifiers (EDFAs) have…
(more)
▼ M.Ing.
Long distance optical communication systems experience a large degree of attenuation due to fibre losses, necessitating signal amplification. Erbium Doped Fibre Amplifiers (EDFAs) have found widespread use as all-fibre optical amplifiers, but exhibit unequal amplification of different wavelengths. Since the gain spectrum is signal-power and pump-power dependent, each EDFA spectrum may differ considerably, and a tuneable gain equalizer is required. A tuneable long-period grating (LPG) can be implemented as a gain equalizer for EDFAs. This dissertation deals with the design of an integrated optic version of the tuneable equalizing filter. The various components of which the device comprises, including optical couplers, Mach-Zehnder interferometers and an LPG, are investigated. The integrated optics designs of these components are then done using the BeamPROP software package. The use and optical properties of germania-doped silica as photosensitive waveguide material is studied. The production of the films for the gain equalizer, using electron-cyclotron resonance plasma-enhanced chemical vapour deposition, is discussed. Characterization of these films was carried out using spectroscopic ellipsometry and infrared spectroscopy. The optical constants, thickness, germania content and hydroxyl absorption was calculated using these measurements.
Subjects/Keywords: Optical amplifiers; Optical fibers; Optical communications
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APA (6th Edition):
Botha, R. (2009). Towards an integrated optic tuneable gain equalizer for erbium-doped fibre amplifiers. (Thesis). University of Johannesburg. Retrieved from http://hdl.handle.net/10210/2153
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Botha, Roelene. “Towards an integrated optic tuneable gain equalizer for erbium-doped fibre amplifiers.” 2009. Thesis, University of Johannesburg. Accessed February 27, 2021.
http://hdl.handle.net/10210/2153.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Botha, Roelene. “Towards an integrated optic tuneable gain equalizer for erbium-doped fibre amplifiers.” 2009. Web. 27 Feb 2021.
Vancouver:
Botha R. Towards an integrated optic tuneable gain equalizer for erbium-doped fibre amplifiers. [Internet] [Thesis]. University of Johannesburg; 2009. [cited 2021 Feb 27].
Available from: http://hdl.handle.net/10210/2153.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Botha R. Towards an integrated optic tuneable gain equalizer for erbium-doped fibre amplifiers. [Thesis]. University of Johannesburg; 2009. Available from: http://hdl.handle.net/10210/2153
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Arizona
3.
Lampen, Sara.
Use of Pupil Mapping for Measurement of Linearly Field-dependent Aberrations
.
Degree: 2013, University of Arizona
URL: http://hdl.handle.net/10150/311473
► Rather than measuring aberrations at several locations across the field to quantify the alignment of an optical system, we show how a simple measurement of…
(more)
▼ Rather than measuring aberrations at several locations across the field to quantify the alignment of an
optical system, we show how a simple measurement of the pupil mapping can be used to measure the off-axis performance of the system. This method uses the Abbe sine condition to relate the mapping between the entrance and the exit pupils, where the violations of the generalized sine condition are used to determine the pupil mapping error. From this pupil mapping, the linearly field-dependent aberrations can be calculated. One of the advantages to this method is that all of the test equipment can be aligned to the center of the field while making measurements of the off-axis performance, which reduces the uncertainty of the measurement. This advantage is particularly evident with systems or sub-systems that have large inherent aberrations where off-axis alignment tolerances are very tight. Additionally, in the Sine Condition Test (SCTest), the test equipment can be designed to compensate for the native Siedel coma in the system. This makes it more straightforward to measure the linearly field dependence of the aberrations. By reducing or removing coma, the measurement uncertainty is further reduced. This work begins by explaining the background of the Abbe sine condition, derivation of the pupil mapping error, and an overview of linearly field-dependent astigmatism that arises from misalignment. Next, the general method of implementation is discussed, and expanded further by exploring the two different source options: a point source with a grating or a flat-panel display. Experimental results from proof of concept systems are shown for both cases. Next, this dissertation explains how the SCTest can be implemented on more complex systems. Last, this dissertation shows how the linear aberrations, along with constant field-dependent aberrations, can be used to align a system. Here, the application of the alignment version of the SCTest on a three mirror anastigmat (TMA) is discussed. Using simulation, this dissertation then investigates the behavior of the alignment SCTest for various levels of mirror misalignment, mirror fabrication errors, and misalignment of the test equipment. All of these tests show that the alignment SCTest can successfully align an
optical system.
Advisors/Committee Members: Burge, James H (advisor), Burge, James H. (committeemember), Dubin, Matthew (committeemember), Hua, Hong (committeemember), Sasin, Jose (committeemember).
Subjects/Keywords: Optical Alignment;
Optical Testing;
Optical Sciences;
Abberrations
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APA ·
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Manager
APA (6th Edition):
Lampen, S. (2013). Use of Pupil Mapping for Measurement of Linearly Field-dependent Aberrations
. (Doctoral Dissertation). University of Arizona. Retrieved from http://hdl.handle.net/10150/311473
Chicago Manual of Style (16th Edition):
Lampen, Sara. “Use of Pupil Mapping for Measurement of Linearly Field-dependent Aberrations
.” 2013. Doctoral Dissertation, University of Arizona. Accessed February 27, 2021.
http://hdl.handle.net/10150/311473.
MLA Handbook (7th Edition):
Lampen, Sara. “Use of Pupil Mapping for Measurement of Linearly Field-dependent Aberrations
.” 2013. Web. 27 Feb 2021.
Vancouver:
Lampen S. Use of Pupil Mapping for Measurement of Linearly Field-dependent Aberrations
. [Internet] [Doctoral dissertation]. University of Arizona; 2013. [cited 2021 Feb 27].
Available from: http://hdl.handle.net/10150/311473.
Council of Science Editors:
Lampen S. Use of Pupil Mapping for Measurement of Linearly Field-dependent Aberrations
. [Doctoral Dissertation]. University of Arizona; 2013. Available from: http://hdl.handle.net/10150/311473
Ryerson University
4.
Pu, Xiaojun (Sean).
Fiber loop ring-down spectroscopy with a long-period grating cavity.
Degree: 2009, Ryerson University
URL: https://digital.library.ryerson.ca/islandora/object/RULA%3A1096
► Cavity Ring-down spectroscopy is an absorption detection technique that makes the[sic]use of an optical cavity to realize a long effective optical path length through a…
(more)
▼ Cavity Ring-down spectroscopy is an absorption detection technique that makes the[sic]use of an
optical cavity to realize a long effective
optical path length through a sample and to render the measurement independent of intensity. These two features give the ring-down spectroscopy many advantages over traditional absorption techniques and allow it to measure chemicals present in trace amount.This thesis presents my study of fiber loop ring-down spectroscopy with a long-period grating (LPG) cavity as the sensing section. There are several advantages in this design: 1) It provides a relatively larger sensing area for the evanescent wave to interact with the environment when compared with a fiber taper and a D-shaped fiber; 2) The LPG cavity has a much lower insertion loss than the micro-cell; and 3) The tensile strength of the fiber is well preserved.Many issues such as the LPG mode order, LPG cavity loss, sample cell design, ring-down pulse detection and analysis have been studied. As an example, the technique was applied to measure the spectral absorption of 1-octyne in decane solution and a detection limit of 0.62% 1-octyne was determined with the exist[ing] experimental setup, which is a fact or 2 better than the result using fiber taper.
Advisors/Committee Members: Gu, Xijia (Thesis advisor), Ryerson University (Degree grantor).
Subjects/Keywords: \Optical spectroscopy; Optical fiber detectors
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Manager
APA (6th Edition):
Pu, X. (. (2009). Fiber loop ring-down spectroscopy with a long-period grating cavity. (Thesis). Ryerson University. Retrieved from https://digital.library.ryerson.ca/islandora/object/RULA%3A1096
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Pu, Xiaojun (Sean). “Fiber loop ring-down spectroscopy with a long-period grating cavity.” 2009. Thesis, Ryerson University. Accessed February 27, 2021.
https://digital.library.ryerson.ca/islandora/object/RULA%3A1096.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Pu, Xiaojun (Sean). “Fiber loop ring-down spectroscopy with a long-period grating cavity.” 2009. Web. 27 Feb 2021.
Vancouver:
Pu X(. Fiber loop ring-down spectroscopy with a long-period grating cavity. [Internet] [Thesis]. Ryerson University; 2009. [cited 2021 Feb 27].
Available from: https://digital.library.ryerson.ca/islandora/object/RULA%3A1096.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Pu X(. Fiber loop ring-down spectroscopy with a long-period grating cavity. [Thesis]. Ryerson University; 2009. Available from: https://digital.library.ryerson.ca/islandora/object/RULA%3A1096
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Rochester
5.
Pettit, Robert Michael.
Optomechanics with optically levitated
nanoparticles.
Degree: PhD, 2020, University of Rochester
URL: http://hdl.handle.net/1802/35479
► Optomechanical systems are currently being developed to study foundational questions in quantum mechanics and to push the limits of precision metrology. One particular challenge in…
(more)
▼ Optomechanical systems are currently being
developed to study foundational
questions in quantum mechanics and
to push the limits of precision metrology.
One particular
challenge in designing an optomechanical experiment,
however, is
the necessary isolation of the test mass from it’s environment.
Environmental coupling often leads to degradation of the desired
mechanical
motion, reducing the system’s sensitivity as a
measurement probe and destroying
any quantum coherence that might
be contained in the motion of
the test mass. To mitigate this
challenge, an optomechanical system based
on optical levitation of
dielectric nanoparticles is constructed. In such a system,
environmental coupling is reduced by levitating the test mass to
void
any need for mechanical tethering, and working in high vacuum
to limit the
influence of background gases on the motion of the
mass. The system is
designed around a free-space optical dipole
trap or optical tweezer, allowing
for easy access to the trapped
particle. Using this platform, a connection
between the motion of
a levitated sphere under the influence of optical feedback
and a
canonical optical laser is discovered, tested, and verified.
Finally, a hybrid system consisting of a levitated nanodiamond with
a single
nitrogen–vacancy defect center providing an electron spin
degree–of–freedom
is considered. Manipulations of the single spin
are performed in low vacuum
and coherence times on the order of
100 ns are observed.
Subjects/Keywords: Optical trapping; Optical tweezer
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APA ·
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Manager
APA (6th Edition):
Pettit, R. M. (2020). Optomechanics with optically levitated
nanoparticles. (Doctoral Dissertation). University of Rochester. Retrieved from http://hdl.handle.net/1802/35479
Chicago Manual of Style (16th Edition):
Pettit, Robert Michael. “Optomechanics with optically levitated
nanoparticles.” 2020. Doctoral Dissertation, University of Rochester. Accessed February 27, 2021.
http://hdl.handle.net/1802/35479.
MLA Handbook (7th Edition):
Pettit, Robert Michael. “Optomechanics with optically levitated
nanoparticles.” 2020. Web. 27 Feb 2021.
Vancouver:
Pettit RM. Optomechanics with optically levitated
nanoparticles. [Internet] [Doctoral dissertation]. University of Rochester; 2020. [cited 2021 Feb 27].
Available from: http://hdl.handle.net/1802/35479.
Council of Science Editors:
Pettit RM. Optomechanics with optically levitated
nanoparticles. [Doctoral Dissertation]. University of Rochester; 2020. Available from: http://hdl.handle.net/1802/35479
University of Johannesburg
6.
Burger, Johan Petrus.
'n Erbiumgedoteerde vesellasersensor met Braggroosterspieëls.
Degree: 2014, University of Johannesburg
URL: http://hdl.handle.net/10210/9178
► M.Eng. (Electrical and Electronic Engineering)
An in-fibre Bragg grating is a period perturbation of the refractive index of the core of an optical fibre, where…
(more)
▼ M.Eng. (Electrical and Electronic Engineering)
An in-fibre Bragg grating is a period perturbation of the refractive index of the core of an optical fibre, where the length of the grating is much longer than the period of the grating. These gratings reflect light in a narrow band around a certain optical frequency. This narrow band is shifted in wavelength when the element is strained and is an absolute measure of the strain state of the grating. One way to interrogate this type of sensor is by using it as a mirror of an optical fibre laser, therefby forcing the laser emission band to coincide with the resonant frequency of the grating. In this thesis a theoretical model was developed to describe the operation of optically pumped Er+-doped optical fibre lasers. An explicit expression for the ouput power for a Fabry Perot fibre laser, was derived for the first time. The intracavity power propagation was also solved numerically. An optical fibre laser consisting out of an Er+-doped optical fibre optically pumped at 980nm, was built. A multilayer dielectric stack mirror was deposited on the one fibre endpoint of the laser. The other reflector is an in-fibre Bragg grating with a peak reflectance of 94% at 1548.5nm and a bandwith of <O.3nm. The buildup of the output power of the laser during the deposition, showed good correlation with the predicted values. The length of the active fibre was also varied, and again the theory could correctly predict the output power as well as the laser pump threshold. A scanning type of Sagnac interferometer was investigated as a possible wavelength demodulation system for the fibre laser sensor. With some alterations this system shows merit as an inexpensive and effective way to monitor the wavelength shifts in in-fibre Bragg gratings.
Subjects/Keywords: Optical fibers; Optical detectors
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APA (6th Edition):
Burger, J. P. (2014). 'n Erbiumgedoteerde vesellasersensor met Braggroosterspieëls. (Thesis). University of Johannesburg. Retrieved from http://hdl.handle.net/10210/9178
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Burger, Johan Petrus. “'n Erbiumgedoteerde vesellasersensor met Braggroosterspieëls.” 2014. Thesis, University of Johannesburg. Accessed February 27, 2021.
http://hdl.handle.net/10210/9178.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Burger, Johan Petrus. “'n Erbiumgedoteerde vesellasersensor met Braggroosterspieëls.” 2014. Web. 27 Feb 2021.
Vancouver:
Burger JP. 'n Erbiumgedoteerde vesellasersensor met Braggroosterspieëls. [Internet] [Thesis]. University of Johannesburg; 2014. [cited 2021 Feb 27].
Available from: http://hdl.handle.net/10210/9178.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Burger JP. 'n Erbiumgedoteerde vesellasersensor met Braggroosterspieëls. [Thesis]. University of Johannesburg; 2014. Available from: http://hdl.handle.net/10210/9178
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Johannesburg
7.
Zhu, Yinian.
Fabrication of long-period gratings and their applications in optical fibre communications and sensing systems.
Degree: 2009, University of Johannesburg
URL: http://hdl.handle.net/10210/2190
► D.Phil.
This dissertation deals with the fabrication, characterisation, and applications of long-period gratings in optical fibre communications and sensing systems. The aim of this project…
(more)
▼ D.Phil.
This dissertation deals with the fabrication, characterisation, and applications of long-period gratings in optical fibre communications and sensing systems. The aim of this project is to assess long-period gratings as media for active or passive fibre devices, particularly as components for the telecommunications industry. A review of the properties and characteristics of fibre gratings associated with the photosensitivity of germanosilicate fibres is provided, which includes a theoretical analysis of the principles of operation for short-period gratings (fibre Bragg gratings) and long-period gratings. The simulations of the spectral response from these two types of gratings are also presented. A number of long-period grating fabrication methods and techniques, which were reported by some researchers, are reviewed. In this project, the normal long-period gratings and phase-shifted long-period gratings are fabricated by using a line-narrowed KrF excimer laser combined with the metal amplitude mask technique. The metal mask is made of a stainless steel sheet, and the slot width (periodicity) is processed by using high quality photographic tooling. Three normal long-period gratings with different periodicities and one phase-shifted long-period grating can be manufactured simultaneously because there are four metal masks imprinted in one inexpensive stainless steel sheet. The mass-production of long-period gratings becomes possible, and the number of gratings that can be written is limited only by the excimer laser beam or metal mask dimension orthogonal to the fibre axis. The fibres that are used in our experiments are photosensitive optical fibres (PS1500). Long-period gratings can be written directly into these fibres without hydrogenation. Two types of long-period grating devices are investigated and developed for applications in dense wavelength division multiplexing (DWDM)networks: erbium-doped fibre amplifier (EDFA) gain-flattening filters and wavelength-tuneable add/drop multiplexers. Firstly, the transmission characteristics of phase-shifted long-period gratings are simulated theoretically by a combination of the coupled-mode theory and the fundamental-matrix method. It is suggested that a phase-shifted long-period grating device cascaded with another normal long-period grating can be used to flatten the gain spectrum of an EDFA containing three gain peaks. The experimental results show that a broad amplifier with peak-to-peak variations of less than 0.7 dB over 36 nm from 1526 to 1562 nm, which covers the entire C-band of the EDFA, can be realized practically. Next, a wavelength-tuneable add/drop multiplexer is designed and configured. In this device, four identical long-period gratings are assembled on piezoelectric ceramic fibre stretchers. The modelling of the device predicts that 50 ITU DWDM-channel signals could be selected in the wavelength range from 1526.25 to 1563.75 nm with 0.75 nm channel spacing and the cross-talk is less than –39 dB while the total insertion loss is about 0.24 dB. There…
Subjects/Keywords: Optical communications; Optical fiber detectors
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APA ·
Chicago ·
MLA ·
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CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Zhu, Y. (2009). Fabrication of long-period gratings and their applications in optical fibre communications and sensing systems. (Thesis). University of Johannesburg. Retrieved from http://hdl.handle.net/10210/2190
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Zhu, Yinian. “Fabrication of long-period gratings and their applications in optical fibre communications and sensing systems.” 2009. Thesis, University of Johannesburg. Accessed February 27, 2021.
http://hdl.handle.net/10210/2190.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Zhu, Yinian. “Fabrication of long-period gratings and their applications in optical fibre communications and sensing systems.” 2009. Web. 27 Feb 2021.
Vancouver:
Zhu Y. Fabrication of long-period gratings and their applications in optical fibre communications and sensing systems. [Internet] [Thesis]. University of Johannesburg; 2009. [cited 2021 Feb 27].
Available from: http://hdl.handle.net/10210/2190.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Zhu Y. Fabrication of long-period gratings and their applications in optical fibre communications and sensing systems. [Thesis]. University of Johannesburg; 2009. Available from: http://hdl.handle.net/10210/2190
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Johannesburg
8.
Menyennett, Calvin.
Constrained sequences and codes for binary asymmetrical optical channels.
Degree: 2014, University of Johannesburg
URL: http://hdl.handle.net/10210/9772
► M.Ing. (Electrical and Electronic Engineering)
During the past decade the optical disc has become increasingly popular. Write-once optical recording systems will mainly be used in…
(more)
▼ M.Ing. (Electrical and Electronic Engineering)
During the past decade the optical disc has become increasingly popular. Write-once optical recording systems will mainly be used in data storage systems in which archival aspects or mass storage requirements prevail. In write-once optical data storage one is faced with an asymmetry between marks and non-marks due to a practical lower limit of the mark size. In some optical fibre communications there is also an asymmetry present in injection lasers and it may be feasible to use asymmetrical codes. In this study information theoretical methods are used to find values of channel capacity for sequences complying with binary asymmetrical runlength constraints. Different coding methods are used to construct encoders and decoders for generating and decoding these sequences with high values of efficiency. The power spectra of maxentropic binary asymmetrical runlength limited sequences complying with different runlength constraints are also investigated.
Subjects/Keywords: Optical communications; Optical disks
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APA (6th Edition):
Menyennett, C. (2014). Constrained sequences and codes for binary asymmetrical optical channels. (Thesis). University of Johannesburg. Retrieved from http://hdl.handle.net/10210/9772
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Menyennett, Calvin. “Constrained sequences and codes for binary asymmetrical optical channels.” 2014. Thesis, University of Johannesburg. Accessed February 27, 2021.
http://hdl.handle.net/10210/9772.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Menyennett, Calvin. “Constrained sequences and codes for binary asymmetrical optical channels.” 2014. Web. 27 Feb 2021.
Vancouver:
Menyennett C. Constrained sequences and codes for binary asymmetrical optical channels. [Internet] [Thesis]. University of Johannesburg; 2014. [cited 2021 Feb 27].
Available from: http://hdl.handle.net/10210/9772.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Menyennett C. Constrained sequences and codes for binary asymmetrical optical channels. [Thesis]. University of Johannesburg; 2014. Available from: http://hdl.handle.net/10210/9772
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Adelaide
9.
Bekteshi, Mustaf Raif.
[EMBARGOED] Mechanical and optical characterisation of glass optical fibres for sensing applications.
Degree: 2019, University of Adelaide
URL: http://hdl.handle.net/2440/121351
► The capacity of glass optical fibres to handle stress experienced in sensing application is critical in many areas including biomedical sensing. Accordingly, it is important…
(more)
▼ The capacity of glass
optical fibres to handle stress experienced in sensing application is critical in many areas including biomedical sensing. Accordingly, it is important to determine the tensile strength of
optical fibre, providing better understanding of
optical fibre strength and the behaviour of
optical fibre under certain stresses. This thesis covers the mechanical and
optical characterisation of a range of solid glass
optical fibres, including solid fibres made of various glass materials, stored lead silicate solid fibre and microstructured
optical fibre made of silica glass material. This thesis employs standard mechanical testing techniques such as tensile testing. Data collected from the tensile strength tests is used to understand the statistical behaviour of solid fibres and characterise them mechanically using the statistical Weibull distribution technique. In addition, the strength of numerous solid glass
optical fibres made of different glass materials are compared. Firstly, data indicates that depending on the glass material, the strength of the fibre under tensile load varies from very high strength for standard telecommunication fibre, such as solid SMF28, to very low strength for ZBLAN fluoride glass fibres. Secondly, using the same statistical technique for data analysis, an investigation of the effect of aging (storage time) in F2 solid glass fibre was carried out. Results indicate that the aging effect does not have significant effect on the strength of solid F2 glass fibres. Additionally, an investigation was undertaken into the effect of capillary hole size (inflation ratio) and presence of multiple holes on the strength of microstructured glass
optical fibres. Results indicate that the inflation ratio and presence of multiple holes in the fibre affects the strength of the fibre. This thesis presents an investigation of the
optical characterisation of solid and hollow core
optical fibres. Raman spectroscopy of the glass materials was also conducted to explore their potential application in biomedical sensing.
Advisors/Committee Members: Ebendorff-Heidepriem, Heike (advisor), Schartner, Erik (advisor), Tsiminis, Georgios (advisor), School of Physical Sciences (school).
Subjects/Keywords: Mechanical; optical; glass optical fibre
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APA (6th Edition):
Bekteshi, M. R. (2019). [EMBARGOED] Mechanical and optical characterisation of glass optical fibres for sensing applications. (Thesis). University of Adelaide. Retrieved from http://hdl.handle.net/2440/121351
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Bekteshi, Mustaf Raif. “[EMBARGOED] Mechanical and optical characterisation of glass optical fibres for sensing applications.” 2019. Thesis, University of Adelaide. Accessed February 27, 2021.
http://hdl.handle.net/2440/121351.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Bekteshi, Mustaf Raif. “[EMBARGOED] Mechanical and optical characterisation of glass optical fibres for sensing applications.” 2019. Web. 27 Feb 2021.
Vancouver:
Bekteshi MR. [EMBARGOED] Mechanical and optical characterisation of glass optical fibres for sensing applications. [Internet] [Thesis]. University of Adelaide; 2019. [cited 2021 Feb 27].
Available from: http://hdl.handle.net/2440/121351.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Bekteshi MR. [EMBARGOED] Mechanical and optical characterisation of glass optical fibres for sensing applications. [Thesis]. University of Adelaide; 2019. Available from: http://hdl.handle.net/2440/121351
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Melbourne
10.
Wang, Peng.
The energy efficiency of EDFA and Raman Fiber Amplifier.
Degree: 2016, University of Melbourne
URL: http://hdl.handle.net/11343/124032
► Optical fibre links using optical amplifiers in combination with advanced modulation formats and Forward Error Correction (FEC) are promising technologies to increase transmission distance as…
(more)
▼ Optical fibre links using optical amplifiers in combination with advanced modulation formats and Forward Error Correction (FEC) are promising technologies to increase transmission distance as well as the capacity of communication systems. The rapidly increasing energy consumption of telecommunication networks is driving network designers to consider how to minimize energy consumption of optical fibre links by choosing the right combination of optical amplifier, advanced modulation format and error correction technology.
This thesis involves development of a model for calculating the lower limit of power consumption of EDFAs when designing an optical fibre link. We compare the energy efficiency of Distributed Raman Fiber Amplifiers (DRFA) and Erbium-Doped Fiber Amplifiers (EDFA) used in long-haul transmission systems. This comparison accounts for the interaction between optical link power, signal quality (as measured by the Bit Error Rate (BER)), and the use of FEC. We show that deploying DRFAs in some scenarios may be more energy efficient than EDFAs, despite their intrinsic requirement for higher pump powers.
Subjects/Keywords: Optical fibre network; Optical amplifier
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APA (6th Edition):
Wang, P. (2016). The energy efficiency of EDFA and Raman Fiber Amplifier. (Masters Thesis). University of Melbourne. Retrieved from http://hdl.handle.net/11343/124032
Chicago Manual of Style (16th Edition):
Wang, Peng. “The energy efficiency of EDFA and Raman Fiber Amplifier.” 2016. Masters Thesis, University of Melbourne. Accessed February 27, 2021.
http://hdl.handle.net/11343/124032.
MLA Handbook (7th Edition):
Wang, Peng. “The energy efficiency of EDFA and Raman Fiber Amplifier.” 2016. Web. 27 Feb 2021.
Vancouver:
Wang P. The energy efficiency of EDFA and Raman Fiber Amplifier. [Internet] [Masters thesis]. University of Melbourne; 2016. [cited 2021 Feb 27].
Available from: http://hdl.handle.net/11343/124032.
Council of Science Editors:
Wang P. The energy efficiency of EDFA and Raman Fiber Amplifier. [Masters Thesis]. University of Melbourne; 2016. Available from: http://hdl.handle.net/11343/124032
University of Arizona
11.
Redman, Brian.
Novel Hybrid Analysis Techniques for Complex Optical Systems
.
Degree: 2019, University of Arizona
URL: http://hdl.handle.net/10150/636578
► Non-traditional designs are being created to meet an increasing need for cheaper, smaller, more accurate, and more robust optical systems. Standard modeling approaches and quality…
(more)
▼ Non-traditional designs are being created to meet an increasing need for cheaper, smaller, more accurate, and more robust
optical systems. Standard modeling approaches and quality metrics do not sufficiently describe these novel designs because the systems break standard assumptions and often require task specific metrics. New modeling and measurement techniques are required to determine the limitations and to improve performance. Many traditional
optical modeling approaches simplify the analysis of
optical systems by make assumptions. Complex
optical systems require modeling methods that are more intensive which limits the development of non-traditional
optical systems. Measurement and simulation frameworks that break up the
optical systems into smaller components can relax the assumption of the simplified
optical approaches without requiring the complexity of more complete approaches. This dissertation presents simulations and experimental measurements that leverage traditional
optical design tools in conjunction with custom analysis methods to quantify the performance of non-traditional
optical systems. The simulation methods and experimental measurements are demonstrated with four unique
optical systems. Fourier processing and Mie theory were used to experimentally connect long-wave infrared image degradation to the properties of fog. Simulations of a snapshot channeled imaging polarimeter derived a fundamental limit for the extinction ratio of polarimeters that encode polarization information into spatially modulated irradiance patterns. Ray tracing and custom processing to combine wavefronts was used to simulate the interferogram of a snapshot Fourier transform spectrometer with spatially and spectral incoherent input. The workflow to designs and simulate a monolithic compressive classification system enabled the automated creation of a task-specific
optical design.
Advisors/Committee Members: Schwiegerling, James (advisor), Milster, Thomas (committeemember), LaCasse, Charles (committeemember).
Subjects/Keywords: interference;
Optical design;
optical simulations
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Manager
APA (6th Edition):
Redman, B. (2019). Novel Hybrid Analysis Techniques for Complex Optical Systems
. (Doctoral Dissertation). University of Arizona. Retrieved from http://hdl.handle.net/10150/636578
Chicago Manual of Style (16th Edition):
Redman, Brian. “Novel Hybrid Analysis Techniques for Complex Optical Systems
.” 2019. Doctoral Dissertation, University of Arizona. Accessed February 27, 2021.
http://hdl.handle.net/10150/636578.
MLA Handbook (7th Edition):
Redman, Brian. “Novel Hybrid Analysis Techniques for Complex Optical Systems
.” 2019. Web. 27 Feb 2021.
Vancouver:
Redman B. Novel Hybrid Analysis Techniques for Complex Optical Systems
. [Internet] [Doctoral dissertation]. University of Arizona; 2019. [cited 2021 Feb 27].
Available from: http://hdl.handle.net/10150/636578.
Council of Science Editors:
Redman B. Novel Hybrid Analysis Techniques for Complex Optical Systems
. [Doctoral Dissertation]. University of Arizona; 2019. Available from: http://hdl.handle.net/10150/636578
Rutgers University
12.
Gatdula, Robert Diaz, 1990-.
Mitigation of loss, crosstalk, and resonance-shift for scalable silicon photonic integrated circuits.
Degree: PhD, Electrical and Computer Engineering, 2019, Rutgers University
URL: https://rucore.libraries.rutgers.edu/rutgers-lib/61747/
► Integrated optical interconnect technology has reached a point in which academia and industry research are dedicating many of its resources to maturing the technology and…
(more)
▼ Integrated optical interconnect technology has reached a point in which academia and industry research are dedicating many of its resources to maturing the technology and developing it for large scalability. Silicon photonics and silicon photonic-related technologies are the main contenders in driving scalability due to silicon’s advantage in being a successful mature material in other large-scale developments such as in achieving highly dense transistors. Silicon’s past success has jumpstarted silicon photonics. However, there are still many hurdles to scaling up.
One of the biggest issues with silicon waveguides is that they can be quite lossy. Despite fabrication processes becoming more advanced, the losses of single-mode silicon waveguides are still several orders worse than that in silica-based optical fibers. Typically, to reach lower losses, designers can widen or thicken silicon waveguides. However, there are various multimode-related caveats that can make this non-trivial. As such, we explore waveguide losses with a multimode perspective and provide some insight to avoid intermodal waveguide scattering that might inadvertently increase loss rather than decrease it in wider waveguides.
Another issue with waveguides is the need to bend them back and forth when routing light to various parts of a photonic integrated circuit. Dense waveguides have been proven to demonstrate low crosstalk in straight sections by creatively engineering the relative width geometry between neighboring waveguides in the form of a waveguide superlattice. However, the bending of waveguide superlattices introduces bending-related physics that can increase the crosstalk. We explore the bending regime and demonstrate dense waveguide superlattice bends of small footprint and relative crosstalk no greater than -19.6 dB for a waveguide superlattice with a minimum bending radius of 5 µm.
We also explore the sensitivities of microring-based transceiver circuits, which can drastically be reduced in performance by fabrication deviations. Furthermore, with ambient conditions such as temperature constantly changing, the performance of microrings can be unstable. More than likely, photonic integrated circuits will be packaged in systems including electronic circuits that can tune the performance of their photonic counterparts. Thus, we provide various gradient-based algorithms to enable automated tuning and thermal adaptivity for multi-microring photonic integrated circuits.
Advisors/Committee Members: Jiang, Wei (chair), Lu, Yicheng (internal member), Caggiano, Michael (internal member), Gajic, Zoran (internal member), Lu, Ming (outside member), School of Graduate Studies.
Subjects/Keywords: Optics; Optical interconnects; Optical losses
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APA (6th Edition):
Gatdula, Robert Diaz, 1. (2019). Mitigation of loss, crosstalk, and resonance-shift for scalable silicon photonic integrated circuits. (Doctoral Dissertation). Rutgers University. Retrieved from https://rucore.libraries.rutgers.edu/rutgers-lib/61747/
Chicago Manual of Style (16th Edition):
Gatdula, Robert Diaz, 1990-. “Mitigation of loss, crosstalk, and resonance-shift for scalable silicon photonic integrated circuits.” 2019. Doctoral Dissertation, Rutgers University. Accessed February 27, 2021.
https://rucore.libraries.rutgers.edu/rutgers-lib/61747/.
MLA Handbook (7th Edition):
Gatdula, Robert Diaz, 1990-. “Mitigation of loss, crosstalk, and resonance-shift for scalable silicon photonic integrated circuits.” 2019. Web. 27 Feb 2021.
Vancouver:
Gatdula, Robert Diaz 1. Mitigation of loss, crosstalk, and resonance-shift for scalable silicon photonic integrated circuits. [Internet] [Doctoral dissertation]. Rutgers University; 2019. [cited 2021 Feb 27].
Available from: https://rucore.libraries.rutgers.edu/rutgers-lib/61747/.
Council of Science Editors:
Gatdula, Robert Diaz 1. Mitigation of loss, crosstalk, and resonance-shift for scalable silicon photonic integrated circuits. [Doctoral Dissertation]. Rutgers University; 2019. Available from: https://rucore.libraries.rutgers.edu/rutgers-lib/61747/
Vanderbilt University
13.
Smith, James Craig.
Optical trapping techniques involving microrheology and Tcell triggering.
Degree: MS, Chemical Engineering, 2012, Vanderbilt University
URL: http://hdl.handle.net/1803/15178
► Since their invention in 1970, optical traps have been used for a wide variety of applications including microrheolgy, dna stretching, as well as being a…
(more)
▼ Since their invention in 1970,
optical traps have been used for a wide variety of applications including microrheolgy, dna stretching, as well as being a useful tool for gaining insight on the mechanics of molecular motors. In this thesis, an
optical trap was used to determine the properties of both a Newtonian and a non-Newtonian fluid. A glycerol/water mixture was tested ranging from 0 weight percent to 95 weight percent glycerol. The data gathered from the
optical trap agreed with results previously published using a rheometer. Xanthan gum was mixed with water ranging from 0.01 weight percent to 0.1 weight percent and tested. The data gathered from the trap matched the results given by the manufacture.
Tcells were triggered by using an
optical trap to apply force upon the Tcell receptor. Oscillatory force along with a step and hold force both were used for the triggering. Oscillatory force required only 5 minutes to trigger while the step and hold approach took over 25 minutes.
Advisors/Committee Members: Matt Lang (committee member).
Subjects/Keywords: Optical Traps
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Manager
APA (6th Edition):
Smith, J. C. (2012). Optical trapping techniques involving microrheology and Tcell triggering. (Thesis). Vanderbilt University. Retrieved from http://hdl.handle.net/1803/15178
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Smith, James Craig. “Optical trapping techniques involving microrheology and Tcell triggering.” 2012. Thesis, Vanderbilt University. Accessed February 27, 2021.
http://hdl.handle.net/1803/15178.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Smith, James Craig. “Optical trapping techniques involving microrheology and Tcell triggering.” 2012. Web. 27 Feb 2021.
Vancouver:
Smith JC. Optical trapping techniques involving microrheology and Tcell triggering. [Internet] [Thesis]. Vanderbilt University; 2012. [cited 2021 Feb 27].
Available from: http://hdl.handle.net/1803/15178.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Smith JC. Optical trapping techniques involving microrheology and Tcell triggering. [Thesis]. Vanderbilt University; 2012. Available from: http://hdl.handle.net/1803/15178
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
14.
Sun, Deqing.
From Pixels to Layers: Joint Motion Estimation and
Segmentation.
Degree: PhD, Computer Science, 2013, Brown University
URL: https://repository.library.brown.edu/studio/item/bdr:320469/
► Estimating image motion, or optical flow, in scenes with multiple moving objects and segmenting the individual moving objects are two fundamental problems in computer vision…
(more)
▼ Estimating image motion, or
optical flow, in scenes
with multiple moving objects and segmenting the individual moving
objects are two fundamental problems in computer vision and have
applications in many fields, including medical imaging, image
processing, graphics, and robotics. Despite decades of extensive
research effort, current methods still tend to produce large
optical flow errors near motion boundaries and in occlusion regions
and falsely merge foreground objects with the background.
A key feature of
optical flow methods is an energy term, or
prior, that prefers spatially smooth flow fields. In this
dissertation, we show that image-dependent and non-local prior
models can better preserve motion boundaries than the widely used
pairwise Markov Random Field (MRF) models. We also demonstrate that
joint motion estimation and segmentation can achieve more accurate
results than the separate treatment of each problem.
First, we formulate fully learnable low-level models of
optical flow and learn the models from training data. Our results
show that image-dependent, steerable models outperform standard MRF
models, especially in recovering motion boundaries. Second, we
perform a quantitative analysis of recent practices in
optical flow
estimation. Median filtering of the flow field is one of the key
features of the most accurate methods and we formalize this as a
non-local smoothness term that integrates information over a large
spatial neighborhood. We further define a weighted non-local
smoothness term that uses both image and motion cues to preserve
motion boundaries. Third, we develop a layered model to segment
moving objects (layers) using image-dependent, continuous support
functions. The method orders each layer in depth and explicitly
models the occlusions between layers and the temporal consistency
of layers. To avoid being trapped in poor local optima, we define a
discrete formulation of our objective function and extend graph
cuts optimization methods to obtain good initial values for the
continuous formulation. The mixed continuous-discrete optimizer can
automatically infer the number of layers and their depth ordering
for a given scene. Experimental results on benchmark datasets
demonstrate the benefits of joint motion estimation and
segmentation via the layered approach.
Advisors/Committee Members: Black, Michael (Director), Sudderth, Erik (Reader), Yair, Weiss (Reader).
Subjects/Keywords: optical flow
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Manager
APA (6th Edition):
Sun, D. (2013). From Pixels to Layers: Joint Motion Estimation and
Segmentation. (Doctoral Dissertation). Brown University. Retrieved from https://repository.library.brown.edu/studio/item/bdr:320469/
Chicago Manual of Style (16th Edition):
Sun, Deqing. “From Pixels to Layers: Joint Motion Estimation and
Segmentation.” 2013. Doctoral Dissertation, Brown University. Accessed February 27, 2021.
https://repository.library.brown.edu/studio/item/bdr:320469/.
MLA Handbook (7th Edition):
Sun, Deqing. “From Pixels to Layers: Joint Motion Estimation and
Segmentation.” 2013. Web. 27 Feb 2021.
Vancouver:
Sun D. From Pixels to Layers: Joint Motion Estimation and
Segmentation. [Internet] [Doctoral dissertation]. Brown University; 2013. [cited 2021 Feb 27].
Available from: https://repository.library.brown.edu/studio/item/bdr:320469/.
Council of Science Editors:
Sun D. From Pixels to Layers: Joint Motion Estimation and
Segmentation. [Doctoral Dissertation]. Brown University; 2013. Available from: https://repository.library.brown.edu/studio/item/bdr:320469/
15.
Li, Yanqiu.
Ultrafast Phenomena on the Nanoscale in Solids: From
Magnetic to Acoustic Phenomena.
Degree: PhD, Physics, 2009, Brown University
URL: https://repository.library.brown.edu/studio/item/bdr:178/
► Access to ultrafast physical phenomena through the use of real-time laser spectroscopy is a vibrant field in science and engineering today. Ultrashort laser pulses with…
(more)
▼ Access to ultrafast physical phenomena through the use
of real-time laser spectroscopy is a vibrant field in science and
engineering today. Ultrashort laser pulses with controlled energy
of sub-picosecond duration can be used to probe fastest events in
atomic, molecular, solid state and biochemical systems. In this
thesis, we employed ultrafast lasers for light-matter interaction
of selected ultrafast electronic, magnetic and acoustic processes
in distinctly different media. One area of interest in this thesis
is the dynamics of electron spins in ferromagnetic materials.
Previous work in our group successfully demonstrated ultrafast
coherent magnetization rotation in the ferromagnetic thin film
triggered by ultrafast
optical pulses. In this thesis we extended
the study of ultrafast spin dynamics to magnetic nanostructures. In
another material system, a nanocomposite of ferromagnetic and noble
metals, we show how noble metal nanoparticles are capable of
greatly enhancing the magneto-
optical response of the hybrid
nanomaterials when excited at their plasmonic resonance wavelength.
We describe the physics that enables the plasmonic resonance
behavior of the noble-metal nanoparticles to improve their
magnetooptical response. While initially focusing on measurements
of the transient magnetooptical effect in the nanocomposites by
ultrashort pulse
optical techniques, we discovered a strongly
competing signature which originated from optically induced
acoustic vibration of the nanoparticles. The pronounced
acousto-
optical transient phenomena led to the study of laser
picosecond ultrasonics. In this part of work we address the
challenges in the conventional picosecond ultrasonic measurements
where the opto-acoustic signals acquired as modulated reflection of
the time-delayed probe beams are small due to small piezo-optic
coefficients. We have investigated the use of a Fabry-Perot
optical
cavity to enhance these signals. The cavity is formed between a
distributed Bragg reflector and a metal thin film sample.
Experimental results for Al and Cu films show enhancement of
acoustic signals by up to two orders of magnitude. This technique
also makes it possible to determine the actual pulse shape of the
returning acoustic echoes inside the metal thin films, thereby
enriching the total amount of information acquired in picosecond
ultrasonic experiments.
Advisors/Committee Members: Nurmikko, Arto (director), Maris, Humphrey (director), Zia, Rashid (reader).
Subjects/Keywords: Optical Cavity
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Export
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Manager
APA (6th Edition):
Li, Y. (2009). Ultrafast Phenomena on the Nanoscale in Solids: From
Magnetic to Acoustic Phenomena. (Doctoral Dissertation). Brown University. Retrieved from https://repository.library.brown.edu/studio/item/bdr:178/
Chicago Manual of Style (16th Edition):
Li, Yanqiu. “Ultrafast Phenomena on the Nanoscale in Solids: From
Magnetic to Acoustic Phenomena.” 2009. Doctoral Dissertation, Brown University. Accessed February 27, 2021.
https://repository.library.brown.edu/studio/item/bdr:178/.
MLA Handbook (7th Edition):
Li, Yanqiu. “Ultrafast Phenomena on the Nanoscale in Solids: From
Magnetic to Acoustic Phenomena.” 2009. Web. 27 Feb 2021.
Vancouver:
Li Y. Ultrafast Phenomena on the Nanoscale in Solids: From
Magnetic to Acoustic Phenomena. [Internet] [Doctoral dissertation]. Brown University; 2009. [cited 2021 Feb 27].
Available from: https://repository.library.brown.edu/studio/item/bdr:178/.
Council of Science Editors:
Li Y. Ultrafast Phenomena on the Nanoscale in Solids: From
Magnetic to Acoustic Phenomena. [Doctoral Dissertation]. Brown University; 2009. Available from: https://repository.library.brown.edu/studio/item/bdr:178/
16.
Biris, Octavian.
Compression of 2-d and 3-d Dynamic Scenes.
Degree: PhD, Electrical Sciences and Computer
Engineering, 2015, Brown University
URL: https://repository.library.brown.edu/studio/item/bdr:419458/
► This thesis is dedicated to exploring compression methods for large dynamic scenes. The first part presents a case study of compressing aerial video using background…
(more)
▼ This thesis is dedicated to exploring compression
methods for large dynamic scenes. The first part presents a case
study of compressing aerial video using background modeling and
JPEG2000. The concepts used in the case study relate to state of
the art compression frameworks and lay down the foundation for the
methods used to compress 4-d scenes in the second part. The algebra
of random variables and multiresolution analysis are used
throughout this thesis as a means of compressing large dynamic
data. The second part of thesis presents a novel method to estimate
dense scene flow using volumetric and probabilistic 3-d models. The
method first reconstructs 3-d models at each time step using images
synchronously captured from multiple views. Then, the 3-d motion
between two consecutive 3-d models is estimated using a formulation
that is the analog of Horn and Schunck’s
optical flow method. This
particular choice of 3-d model representation allows estimat- ing
highly dense scene flow results, tracking of surfaces undergoing
topological change and reliably recovering large motion
displacements. The benefits of the method and the accuracy of 3-d
flow results are demonstrated on recent multi-view datasets. The
second goal of this work is to compress and reconstruct 3-d scenes
at various time points using the estimated flow. A new method of
scene warping is proposed that involves partitioning the
optical
flow field in regions of coherent motion which are subsequently
parametrized by affine transformations. The compression objective
of this work is achieved by the low storage requirements of the
affine parameters that describe the
optical flow field and the
efficient reconstruction method through warping.
Advisors/Committee Members: Mundy, Joseph (Director), Taubin, Gabriel (Reader), Felzenzswalb, Pedro (Reader).
Subjects/Keywords: Optical Flow
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Export
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Manager
APA (6th Edition):
Biris, O. (2015). Compression of 2-d and 3-d Dynamic Scenes. (Doctoral Dissertation). Brown University. Retrieved from https://repository.library.brown.edu/studio/item/bdr:419458/
Chicago Manual of Style (16th Edition):
Biris, Octavian. “Compression of 2-d and 3-d Dynamic Scenes.” 2015. Doctoral Dissertation, Brown University. Accessed February 27, 2021.
https://repository.library.brown.edu/studio/item/bdr:419458/.
MLA Handbook (7th Edition):
Biris, Octavian. “Compression of 2-d and 3-d Dynamic Scenes.” 2015. Web. 27 Feb 2021.
Vancouver:
Biris O. Compression of 2-d and 3-d Dynamic Scenes. [Internet] [Doctoral dissertation]. Brown University; 2015. [cited 2021 Feb 27].
Available from: https://repository.library.brown.edu/studio/item/bdr:419458/.
Council of Science Editors:
Biris O. Compression of 2-d and 3-d Dynamic Scenes. [Doctoral Dissertation]. Brown University; 2015. Available from: https://repository.library.brown.edu/studio/item/bdr:419458/
17.
Boutin, Molly E.
Advancing in vivo-relevant neural platforms using optical
clearing techniques and self-assembled microtissues.
Degree: PhD, Biomedical Engineering, 2016, Brown University
URL: https://repository.library.brown.edu/studio/item/bdr:674284/
► The central nervous system (CNS) contains a complex assortment of cell types and extracellular matrix proteins, which are arranged into an intricate architecture and ultimately…
(more)
▼ The central nervous system (CNS) contains a complex
assortment of cell types and extracellular matrix proteins, which
are arranged into an intricate architecture and ultimately
cooperate to generate brain function. Many aspects of neural
development and pathology remain elusive, hindering the complete
understanding of neurodevelopmental processes and the development
of therapeutics. Increased understanding of CNS tissues can be
gained by studying neural cells in vitro. In this thesis we aimed
to create in vitro models which approximate important
characteristics of in vivo neural tissue, including tissue
stiffness, cell density, cell composition complexity, and
three-dimensional (3D) cell growth. These characteristics are known
to influence cell behavior, and are challenging to study in
traditional two-dimensional culture models. Using cellular
self-assembly, we created 3D scaffold-free spheroid microtissues
from primary postnatal rat cortical cells. Due to the high cellular
density and
optical opacity of 3D spheroids, traditional confocal
imaging protocols do not allow for visualization of structures in
spheroid centers. Through the application of traditional
neuroscience
optical clearing protocols to neural microtissues, we
increase imaging depth abilities from ~20 µm to ~100 µm.
Improvements in imaging abilities allowed for further
characterization of cortical spheroids, including the
identification of specific cell types, such as neurons, glial
subtypes, neural progenitor cells, and endothelial cells.
Additionally, through single cell patch-clamping and atomic force
microscopy, we characterized and demonstrated the in vivo-relevance
of neuronal electrophysiology and tissue stiffness, respectively.
Following these general characterization studies, we focused on the
specific phenomena of neural vasculature growth. These studies were
motivated by the importance of vasculature in healthy neural
tissue, and the lack of understanding of vascular pathologies
associated with many neurological diseases. We observed the
formation of endothelial cell capillary-like networks within
cortical spheroids, and characterized the presence of extracellular
matrix basement membrane proteins, endothelial cell lumens, and
interactions with relevant resident cell types. Overall, the
studies of this thesis advance in vivo-relevant 3D neural
microtissue models, by improving imaging techniques and providing
characterizations of cell types and relevant tissue
properties.
Advisors/Committee Members: Hoffman-Kim, Diane (Director), Morgan, Jeffrey (Reader), Morrow, Eric (Reader), Franck, Christian (Reader), Vaccarino, Flora (Reader).
Subjects/Keywords: optical clearing
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APA (6th Edition):
Boutin, M. E. (2016). Advancing in vivo-relevant neural platforms using optical
clearing techniques and self-assembled microtissues. (Doctoral Dissertation). Brown University. Retrieved from https://repository.library.brown.edu/studio/item/bdr:674284/
Chicago Manual of Style (16th Edition):
Boutin, Molly E. “Advancing in vivo-relevant neural platforms using optical
clearing techniques and self-assembled microtissues.” 2016. Doctoral Dissertation, Brown University. Accessed February 27, 2021.
https://repository.library.brown.edu/studio/item/bdr:674284/.
MLA Handbook (7th Edition):
Boutin, Molly E. “Advancing in vivo-relevant neural platforms using optical
clearing techniques and self-assembled microtissues.” 2016. Web. 27 Feb 2021.
Vancouver:
Boutin ME. Advancing in vivo-relevant neural platforms using optical
clearing techniques and self-assembled microtissues. [Internet] [Doctoral dissertation]. Brown University; 2016. [cited 2021 Feb 27].
Available from: https://repository.library.brown.edu/studio/item/bdr:674284/.
Council of Science Editors:
Boutin ME. Advancing in vivo-relevant neural platforms using optical
clearing techniques and self-assembled microtissues. [Doctoral Dissertation]. Brown University; 2016. Available from: https://repository.library.brown.edu/studio/item/bdr:674284/
Hong Kong University of Science and Technology
18.
Lei, Ting.
Silicon photonic devices for sensing and microparticle manipulation.
Degree: 2013, Hong Kong University of Science and Technology
URL: http://repository.ust.hk/ir/Record/1783.1-61766
;
https://doi.org/10.14711/thesis-b1251896
;
http://repository.ust.hk/ir/bitstream/1783.1-61766/1/th_redirect.html
► Lab-on-a-chip (LOC) devices are portable, easy-to-use and low-cost for refractive index sensing and bioparticle sorting in tiny volume samples. Optofluidics combining integrated photonics and microfluidics…
(more)
▼ Lab-on-a-chip (LOC) devices are portable, easy-to-use and low-cost for refractive index sensing and bioparticle sorting in tiny volume samples. Optofluidics combining integrated photonics and microfluidics is a promising technology for LOC due to its features of miniaturization, high sensitivity and mass production. In this thesis, we propose and demonstrate silicon photonic device-based refractive index sensors and optical tweezers arrays as building blocks for optofluidics. On the refractive index sensor front, we propose coupled-resonator optical waveguide (CROW)-based sensors for refractive index sensing using spatial domain detection. The conventional optical sensors are typically based on resonance wavelength shift detection in spectral domain. The measurements rely on bulky and expensive equipment (wavelength-tunable laser or spectrometer) which are not suitable for LOC applications. The CROW sensors exhibit broadband transmissions with split modes corresponding to the eigen states. In the spatial domain, the internal field distributions along the CROW show distinguished patterns at different eigen states. Therefore, the refractive index change could be detected spatially by pattern recognitions at fixed probe wavelength. We fabricate racetrack microring cavity CROW sensors in silicon-on-insulator (SOI) substrates. The light scattering from each cavity is captured by an infrared camera and integrated as a pixel to represent the internal field spatial distribution of the CROW. By identifying the pixelized spatial patterns through the fourier transform algorithm, we demonstrate an 8-element CROW sensor with a detection limit of 0.0082 RIU corresponding to 5% mass concentration change of NaCl solutions. We also demonstrate proof-of-concept sensing experiment using gaplessly coupled microdisk CROW on silicon nitride-on-silica substrates. On the optical tweezers array front, we invent Silicon-on-insulator Multimode-interference (MMI) waveguide-based ARrayed optical Tweezers (SMART) technique for two-dimensional microparticle trapping and manipulation. The two-dimensional optical tweezers or optical lattices are significant tools for trapping multiple particles simultaneously and sorting particles by size or refractive index differences. The optical lattice generation techniques (acousto-optic deflectors and holographic optical tweezers) usually require electro-optical devices and sophisticated optics which cannot be integrated into a LOC system. We utilize the self-imaging phenomena in the MMI waveguide to generate optical lattices. We demonstrate arrayed trapping of 1μm- and 2.2μm-sized polystyrene particles in a microfluidic cell with static fluidic. We simulate the multiple physical processes involved in the SMART technique including optical force, thermal-induced flow and fluidic force using the finite-element method. We demonstrate moving, splitting and combining of clusters of microparticles by shaping the optical tweezers array. We also demonstrate 2.2μm polystyrene particle fractionation in optical lattices…
Subjects/Keywords: Optical fiber detectors
; Optical wave guides
; Optical resonance
; Silicon
; Optical properties
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APA (6th Edition):
Lei, T. (2013). Silicon photonic devices for sensing and microparticle manipulation. (Thesis). Hong Kong University of Science and Technology. Retrieved from http://repository.ust.hk/ir/Record/1783.1-61766 ; https://doi.org/10.14711/thesis-b1251896 ; http://repository.ust.hk/ir/bitstream/1783.1-61766/1/th_redirect.html
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Chicago Manual of Style (16th Edition):
Lei, Ting. “Silicon photonic devices for sensing and microparticle manipulation.” 2013. Thesis, Hong Kong University of Science and Technology. Accessed February 27, 2021.
http://repository.ust.hk/ir/Record/1783.1-61766 ; https://doi.org/10.14711/thesis-b1251896 ; http://repository.ust.hk/ir/bitstream/1783.1-61766/1/th_redirect.html.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
MLA Handbook (7th Edition):
Lei, Ting. “Silicon photonic devices for sensing and microparticle manipulation.” 2013. Web. 27 Feb 2021.
Vancouver:
Lei T. Silicon photonic devices for sensing and microparticle manipulation. [Internet] [Thesis]. Hong Kong University of Science and Technology; 2013. [cited 2021 Feb 27].
Available from: http://repository.ust.hk/ir/Record/1783.1-61766 ; https://doi.org/10.14711/thesis-b1251896 ; http://repository.ust.hk/ir/bitstream/1783.1-61766/1/th_redirect.html.
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
Council of Science Editors:
Lei T. Silicon photonic devices for sensing and microparticle manipulation. [Thesis]. Hong Kong University of Science and Technology; 2013. Available from: http://repository.ust.hk/ir/Record/1783.1-61766 ; https://doi.org/10.14711/thesis-b1251896 ; http://repository.ust.hk/ir/bitstream/1783.1-61766/1/th_redirect.html
Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation
University of Melbourne
19.
Li, An.
Investigation of advanced modulation and multiplexing schemes for high-capacity optical transmission.
Degree: 2012, University of Melbourne
URL: http://hdl.handle.net/11343/37761
► Space-division multiplexed (SDM) transmission based on multi-core (MCF) or multi-mode fibre (MMF) emerges as one of the promising solutions for overcoming the capacity limit of…
(more)
▼ Space-division multiplexed (SDM) transmission based on multi-core (MCF) or multi-mode fibre (MMF) emerges as one of the promising solutions for overcoming the capacity limit of standard single mode fibre (SSMF). However, to unleash the full potential of the high data rate SDM transmission, brand-new research on the device to system level is required. In this thesis, we elucidate the overall system architecture, critical components and sub-system modules for mode-division multiplexed (MDM) transmission and report our latest demonstration of MDM superchannel transmission based on few-mode fibre (FMF). We envisage that the combination of MDM and OFDM modulation could provide a viable pathway to the future Tb/s and beyond optical transports.
We first review the basic concepts and principles of conventional optical OFDM system. We introduce two novel variants of coherent optical OFDM (CO-OFDM) system, namely the wavelet packet transform based OFDM (WPT-OFDM) and discrete Fourier transform based OFDM (DFTS-OFDM). The performance of the two new systems are analysed and compared with conventional CO-OFDM system. We next look at the most basic but important element for the SDM transmission system – FMF few-mode fibre (FMF).We then show an experimental demonstration of characterization of physical property of a custom-designed TMF fibre. After that we investigate a broad range of issues on SDM -especially the MDM based on MMF or FMF - from its fundamentals to some of the critical FMF components including mode stripper, mode converter, mode combiner and few-mode amplifiers. With these few-mode components and subsystem module available, we then show experimental demonstrations of MDM transmission over TMF fibre under three different unique MDM schemes:(1) LP01/LP11 mode, (2) dual-LP11 mode, and (3) triple-mode (LP01+LP11a+LP11b). Finally, the research outcome in this thesis is summarized and a few research directions toward future work are presented.
Subjects/Keywords: optical communcations
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APA (6th Edition):
Li, A. (2012). Investigation of advanced modulation and multiplexing schemes for high-capacity optical transmission. (Doctoral Dissertation). University of Melbourne. Retrieved from http://hdl.handle.net/11343/37761
Chicago Manual of Style (16th Edition):
Li, An. “Investigation of advanced modulation and multiplexing schemes for high-capacity optical transmission.” 2012. Doctoral Dissertation, University of Melbourne. Accessed February 27, 2021.
http://hdl.handle.net/11343/37761.
MLA Handbook (7th Edition):
Li, An. “Investigation of advanced modulation and multiplexing schemes for high-capacity optical transmission.” 2012. Web. 27 Feb 2021.
Vancouver:
Li A. Investigation of advanced modulation and multiplexing schemes for high-capacity optical transmission. [Internet] [Doctoral dissertation]. University of Melbourne; 2012. [cited 2021 Feb 27].
Available from: http://hdl.handle.net/11343/37761.
Council of Science Editors:
Li A. Investigation of advanced modulation and multiplexing schemes for high-capacity optical transmission. [Doctoral Dissertation]. University of Melbourne; 2012. Available from: http://hdl.handle.net/11343/37761
University of Arizona
20.
Wilhite, Jeffrey Ryan.
Characterizing the Transient and Stationary Response of the TAU 2 Camera
.
Degree: 2016, University of Arizona
URL: http://hdl.handle.net/10150/612460
► The purpose of this research is to learn how a FLIR Tau 2 infrared camera reacts to stimuli to, later on, preform a calibration of…
(more)
▼ The purpose of this research is to learn how a FLIR Tau 2 infrared camera reacts to stimuli to, later on, preform a calibration of the camera. This included measuring the line spread function (LSF), quantifying the thermal blooming, looking at the response to thermal changes in the focal plane array (FPA), and measuring the response of different temperature and speed sub-pixel objects streaking across the FPA to backtrack what the actual size, speed, shape and temperature of unknown objects were. This work will provide information to help in performing a calibration on the camera necessary to be able to get performance similar to that of a cooled sensor out of an uncooled sensor. There was not enough time to fully understand the reaction of the camera to different stimuli, which would require much more effort, but there was a large amount of information gathered that can greatly increase the understanding of the camera and help in performing calibration of the camera later on.
Advisors/Committee Members: Schwiegerling, Jim (advisor), Norwood, Robert (committeemember), Crawford, Dan (committeemember).
Subjects/Keywords: Optical Sciences
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Manager
APA (6th Edition):
Wilhite, J. R. (2016). Characterizing the Transient and Stationary Response of the TAU 2 Camera
. (Masters Thesis). University of Arizona. Retrieved from http://hdl.handle.net/10150/612460
Chicago Manual of Style (16th Edition):
Wilhite, Jeffrey Ryan. “Characterizing the Transient and Stationary Response of the TAU 2 Camera
.” 2016. Masters Thesis, University of Arizona. Accessed February 27, 2021.
http://hdl.handle.net/10150/612460.
MLA Handbook (7th Edition):
Wilhite, Jeffrey Ryan. “Characterizing the Transient and Stationary Response of the TAU 2 Camera
.” 2016. Web. 27 Feb 2021.
Vancouver:
Wilhite JR. Characterizing the Transient and Stationary Response of the TAU 2 Camera
. [Internet] [Masters thesis]. University of Arizona; 2016. [cited 2021 Feb 27].
Available from: http://hdl.handle.net/10150/612460.
Council of Science Editors:
Wilhite JR. Characterizing the Transient and Stationary Response of the TAU 2 Camera
. [Masters Thesis]. University of Arizona; 2016. Available from: http://hdl.handle.net/10150/612460
University of Arizona
21.
Patil, Raj.
Deep UV Raman Spectroscopy
.
Degree: 2016, University of Arizona
URL: http://hdl.handle.net/10150/613378
► This thesis examines the performance of a custom built deep UV laser (257.5nm) for Raman spectroscopy and the advantages of Raman spectroscopy with a laser…
(more)
▼ This thesis examines the performance of a custom built deep UV laser (257.5nm) for Raman spectroscopy and the advantages of Raman spectroscopy with a laser in the deep UV over a laser in the visible range (532 nm). It describes the theory of resonance Raman scattering, the experimental setup for Raman spectroscopy and a few Raman spectroscopy measurements. The measurements were performed on biological samples oak tree leaf and lactobacillus acidophilus and bifidobacteria from probotioc medicinal capsules. Fluorescence free Raman spectra were acquired for the two samples with 257.5 nm laser. The Raman spectra for the two samples with a 532nm laser was masked with fluorescence. Raman measurements for an inorganic salt sodium nitrate showed a resonance Raman effect with 257.5 nm laser which led to enhancement in the Raman intensity as compared to that with 532 nm laser. Therefore we were able to demonstrate two advantages of deep UV Raman spectroscopy. First one is the possibility of acquiring fluorescence free spectra for biological samples. Second is the possibility of gaining enhancement in Raman intensity due to resonance Raman effect. It was observed that 257.5 nm laser requires optimization to reduce the bandwidth of the laser to get better resolution. The 257.5 nm laser also needs to be optimized to obtain higher power to get better signal to noise ratio. The experimental setup can also be further improved to obtain better resolution. If the improvements required in the setup are implemented, the deep UV Raman setup will become an important tool for spectroscopy.
Advisors/Committee Members: Kieu, Khanh Q (advisor), Norwood, Robert A. (committeemember), Jones, Ronald J. (committeemember).
Subjects/Keywords: Optical Sciences
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Manager
APA (6th Edition):
Patil, R. (2016). Deep UV Raman Spectroscopy
. (Masters Thesis). University of Arizona. Retrieved from http://hdl.handle.net/10150/613378
Chicago Manual of Style (16th Edition):
Patil, Raj. “Deep UV Raman Spectroscopy
.” 2016. Masters Thesis, University of Arizona. Accessed February 27, 2021.
http://hdl.handle.net/10150/613378.
MLA Handbook (7th Edition):
Patil, Raj. “Deep UV Raman Spectroscopy
.” 2016. Web. 27 Feb 2021.
Vancouver:
Patil R. Deep UV Raman Spectroscopy
. [Internet] [Masters thesis]. University of Arizona; 2016. [cited 2021 Feb 27].
Available from: http://hdl.handle.net/10150/613378.
Council of Science Editors:
Patil R. Deep UV Raman Spectroscopy
. [Masters Thesis]. University of Arizona; 2016. Available from: http://hdl.handle.net/10150/613378
University of Arizona
22.
Lin, Likun.
SDN-Enabled Dynamic Feedback Control and Sensing in Agile Optical Networks
.
Degree: 2016, University of Arizona
URL: http://hdl.handle.net/10150/613595
► Fiber optic networks are no longer just pipelines for transporting data in the long haul backbone. Exponential growth in traffic in metro-regional areas has pushed…
(more)
▼ Fiber optic networks are no longer just pipelines for transporting data in the long haul backbone. Exponential growth in traffic in metro-regional areas has pushed higher capacity fiber toward the edge of the network, and highly dynamic patterns of heterogeneous traffic have emerged that are often bursty, severely stressing the historical "fat and dumb pipe" static
optical network, which would need to be massively over-provisioned to deal with these loads. What is required is a more intelligent network with a span of control over the
optical as well as electrical transport mechanisms which enables handling of service requests in a fast and efficient way that guarantees quality of service (QoS) while optimizing capacity efficiency. An "agile"
optical network is a reconfigurable
optical network comprised of high speed intelligent control system fed by real-time in situ network sensing. It provides fast response in the control and switching of
optical signals in response to changing traffic demands and network conditions. This agile control of
optical signals is enabled by pushing switching decisions downward in the network stack to the physical layer. Implementing such agility is challenging due to the response dynamics and interactions of signals in the physical layer. Control schemes must deal with issues such as dynamic power equalization, EDFA transients and cascaded noise effects, impairments due to self-phase modulation and dispersion, and channel-to-channel cross talk. If these issues are not properly predicted and mitigated, attempts at dynamic control can drive the
optical network into an unstable state. In order to enable high speed actuation of signal modulators and switches, the network controller must be able to make decisions based on predictive models. In this thesis, we consider how to take advantage of Software Defined Networking (SDN) capabilities for network reconfiguration, combined with embedded models that access updates from deployed network monitoring sensors. In order to maintain signal quality while optimizing network resources, we find that it is essential to model and update estimates of the physical link impairments in real-time. In this thesis, we consider the key elements required to enable an agile
optical network, with contributions as follows: *Control Framework: extended the SDN concept to include the
optical transport network through extensions to the OpenFlow (OF) protocol. A unified SDN control plane is built to facilitate control and management capability across the electrical/packet-switched and
optical/circuit-switched portions of the network seamlessly. The SDN control plane serves as a platform to abstract the resources of multilayer/multivendor networks. Through this platform, applications can dynamically request the network resources to meet their service requirements. *Use of In-situ Monitors: enabled real-time physical impairment sensing in the control plane using in-situ
Optical Performance Monitoring (OPM) and bit error rate (BER) analyzers. OPM and BER values are used…
Advisors/Committee Members: Wissinger, John W (advisor), Cvijetic, Milorad (committeemember), Lacomb, Lloyd J., Jr. (committeemember).
Subjects/Keywords: Optical Sciences
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Manager
APA (6th Edition):
Lin, L. (2016). SDN-Enabled Dynamic Feedback Control and Sensing in Agile Optical Networks
. (Masters Thesis). University of Arizona. Retrieved from http://hdl.handle.net/10150/613595
Chicago Manual of Style (16th Edition):
Lin, Likun. “SDN-Enabled Dynamic Feedback Control and Sensing in Agile Optical Networks
.” 2016. Masters Thesis, University of Arizona. Accessed February 27, 2021.
http://hdl.handle.net/10150/613595.
MLA Handbook (7th Edition):
Lin, Likun. “SDN-Enabled Dynamic Feedback Control and Sensing in Agile Optical Networks
.” 2016. Web. 27 Feb 2021.
Vancouver:
Lin L. SDN-Enabled Dynamic Feedback Control and Sensing in Agile Optical Networks
. [Internet] [Masters thesis]. University of Arizona; 2016. [cited 2021 Feb 27].
Available from: http://hdl.handle.net/10150/613595.
Council of Science Editors:
Lin L. SDN-Enabled Dynamic Feedback Control and Sensing in Agile Optical Networks
. [Masters Thesis]. University of Arizona; 2016. Available from: http://hdl.handle.net/10150/613595
University of Arizona
23.
Demir, Veysi.
Nanocomposites for High-Speed Optical Modulators and Plasmonic Thermal Mid-Infrared Emitters
.
Degree: 2015, University of Arizona
URL: http://hdl.handle.net/10150/581130
► Demand for high-speed optical modulators and narrow-bandwidth infrared thermal emitters for numerous applications continues to rise and new optical devices are needed to deal with…
(more)
▼ Demand for high-speed
optical modulators and narrow-bandwidth infrared thermal emitters for numerous applications continues to rise and new
optical devices are needed to deal with massive data flows, processing powers, and fabrication costs. Conventional techniques are usually hindered by material limitations or electronic interconnects and advances in organic nanocomposite materials and their integration into photonic integrated circuits (PICs) have been acknowledged as a promising alternative to single crystal techniques. The work presented in this thesis uses plasmonic and magneto-optic effects towards the development of novel
optical devices for harnessing light and generating high bandwidth signals (> 40GHz) at room and cryogenic temperatures (4.2°K). Several publications have resulted from these efforts and are listed at the end of the abstract. In our first published research we developed a narrow-bandwidth mid-infrared thermal emitter using an Ag/dielectric/Ag thin film structure arranged in hexagonal planar lattice structures. PECVD produced nanoamorphous carbon (NAC) is used as a dielectric layer. Spectrally tunable (>2 μm) and narrow bandwidth (<0.5 μm) emission peaks in the range of 4-7μm were demonstrated by decreasing the resistivity of NAC from 10¹² and 10⁹ Ω.cm with an MoSi₂ dopant and increasing the emitter lattice constant from 4 to 7 μm. This technique offers excellent flexibility for developing cost-effective mid-IR sources as compared to costly fiber and quantum cascade lasers (QCLs). Next, the effect of temperature on the Verdet constant for cobalt-ferrite polymer nanocomposites was measured for a series of temperatures ranging from 40 to 200°K with a Faraday rotation polarimeter. No visual change was observed in the films during thermal cycling, and ~4x improvement was achieved at 40°K. The results are promising and further analysis is merited at 4.2°K to assess the performance of this material for cryogenic magneto-optic modulators for supercomputers. Finally, the dielectric constant and loss tangent of MAPTMS sol-gel films were measured over a wide range of microwave frequencies. The test structures were prepared by spin-coating sol-gel films onto metallized glass substrates. The dielectric properties of the sol-gel were probed with several different sets of coplanar waveguides (CPWs) electroplated onto sol-gel films. The dielectric constant and loss-tangent of these films were determined to be ~3.1 and 3 x 10⁻³ at 35GHz. These results are very promising indicating that sol-gels are viable cladding materials for high-speed electro-optic polymer modulators (>40GHz).
Advisors/Committee Members: Peyghambarian, Nasser (advisor), Peyghambarian, Nasser (committeemember), Norwood, Robert A. (committeemember), Pau, Stanley (committeemember).
Subjects/Keywords: Optical Sciences
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Export
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Manager
APA (6th Edition):
Demir, V. (2015). Nanocomposites for High-Speed Optical Modulators and Plasmonic Thermal Mid-Infrared Emitters
. (Doctoral Dissertation). University of Arizona. Retrieved from http://hdl.handle.net/10150/581130
Chicago Manual of Style (16th Edition):
Demir, Veysi. “Nanocomposites for High-Speed Optical Modulators and Plasmonic Thermal Mid-Infrared Emitters
.” 2015. Doctoral Dissertation, University of Arizona. Accessed February 27, 2021.
http://hdl.handle.net/10150/581130.
MLA Handbook (7th Edition):
Demir, Veysi. “Nanocomposites for High-Speed Optical Modulators and Plasmonic Thermal Mid-Infrared Emitters
.” 2015. Web. 27 Feb 2021.
Vancouver:
Demir V. Nanocomposites for High-Speed Optical Modulators and Plasmonic Thermal Mid-Infrared Emitters
. [Internet] [Doctoral dissertation]. University of Arizona; 2015. [cited 2021 Feb 27].
Available from: http://hdl.handle.net/10150/581130.
Council of Science Editors:
Demir V. Nanocomposites for High-Speed Optical Modulators and Plasmonic Thermal Mid-Infrared Emitters
. [Doctoral Dissertation]. University of Arizona; 2015. Available from: http://hdl.handle.net/10150/581130
University of Arizona
24.
Sullivan, John Joseph.
Non-Null Interferometer for Testing of Aspheric Surfaces
.
Degree: 2015, University of Arizona
URL: http://hdl.handle.net/10150/594367
► The use of aspheric surfaces in optical designs can allow for improved performance with fewer optical elements. Their use has become common place due to…
(more)
▼ The use of aspheric surfaces in
optical designs can allow for improved performance with fewer
optical elements. Their use has become common place due to advancements in
optical manufacturing technologies. Standard interferometric testing of aspheric surfaces makes use of part specific null optics in order to match the test wavefront to the aspheric surface under test. Non-null interferometric testing offers the possibility to test a range of aspheric surfaces with a single interferometer design without the need for part specific null optics. However, non-null tests can generate interferograms with very high fringe frequencies that must be resolved and unwrapped, wavefronts with large slopes that must be imaged without vignetting, and induced aberrations which must be separated from the surface errors of the part. The main goal of this project was the construction of a non-null interferometer capable of testing the aspheric tooling used in the manufacturing of soft contact lenses. Sub-Nyquist interferometry was used to allow for large wavefront departures which generate high fringe frequency interferograms to be both captured and unwrapped. The sparse array sensor at the heart of the Sub-Nyquist technique sets limits on both the range of the parts to be tested and the design of the interferometer. Characterization of the interferometer was achieved through the reverse optimization and reverse ray tracing of a model of the interferometer and was aided by multiple measurements of the test part at shifted positions. The system was found to be capable of measuring parts with aspheric departure of over 60λ from the best fit sphere, which with introduced part shifts, generated over 300λ of OPD at the detector. The OPD introduced by the parts was measured to an accuracy of at least 0.76λ peak to valley and 0.12λ rms.
Advisors/Committee Members: Greivenkamp, John E (advisor), Greivenkamp, John E. (committeemember), Sasián, José (committeemember), Wyant, James C. (committeemember).
Subjects/Keywords: Optical Sciences
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Export
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Manager
APA (6th Edition):
Sullivan, J. J. (2015). Non-Null Interferometer for Testing of Aspheric Surfaces
. (Doctoral Dissertation). University of Arizona. Retrieved from http://hdl.handle.net/10150/594367
Chicago Manual of Style (16th Edition):
Sullivan, John Joseph. “Non-Null Interferometer for Testing of Aspheric Surfaces
.” 2015. Doctoral Dissertation, University of Arizona. Accessed February 27, 2021.
http://hdl.handle.net/10150/594367.
MLA Handbook (7th Edition):
Sullivan, John Joseph. “Non-Null Interferometer for Testing of Aspheric Surfaces
.” 2015. Web. 27 Feb 2021.
Vancouver:
Sullivan JJ. Non-Null Interferometer for Testing of Aspheric Surfaces
. [Internet] [Doctoral dissertation]. University of Arizona; 2015. [cited 2021 Feb 27].
Available from: http://hdl.handle.net/10150/594367.
Council of Science Editors:
Sullivan JJ. Non-Null Interferometer for Testing of Aspheric Surfaces
. [Doctoral Dissertation]. University of Arizona; 2015. Available from: http://hdl.handle.net/10150/594367
25.
Chaix, Cécile.
AdaptiSPECT: a Preclinical Imaging System
.
Degree: 2015, University of Arizona
URL: http://hdl.handle.net/10150/594908
► This dissertation addresses the design, development, calibration and performance evaluation of a pre-clinical imaging system called AdaptiSPECT. Single-Photon Emission Computed Tomography (SPECT) systems are powerful…
(more)
▼ This dissertation addresses the design, development, calibration and performance evaluation of a pre-clinical imaging system called AdaptiSPECT. Single-Photon Emission Computed Tomography (SPECT) systems are powerful tools for multiple applications in small-animal research, ranging from drug discovery to fundamental biology. Traditionally, pinhole SPECT systems are designed with fixed imaging characteristics in terms of sensitivity, resolution and size of the field of view, that are dictated by the hardware configuration of the system. The SPECT system described in this dissertation can change its hardware configuration in response to the
subject data it is acquiring in order to improve the imaging performance. We employed 16 modular gamma-ray detectors, each of which consists of a NaI:Tl scintillation crystal, a fused silica lightguide, and an array of 9 PMTs. The camera is designed to work with maximum-likelihood position estimation methods. These detectors are arranged into 2 rings of 8 detectors around an adjustable pinhole aperture. The aperture itself comprises three cylinders of different diameters, each with pinholes of different diameters. The three aperture cylinders are stacked together along the imager axis, and selection of the appropriate ring of pinholes is carried out by translating the entire aperture assembly. In addition, some sections of the aperture are fitted with shutters to open or close additional pinholes that increase sensitivity. We reviewed the method used to calibrate AdaptiSPECT, and proposed a new interpolation scheme specific to adaptive SPECT imaging systems where the detectors can move to multiple locations, that yields system matrices for any configuration employed during adaptive imaging. We evaluated the performances of AdaptiSPECT for various configurations. The magnification of the system ranges from 1.2 to 11.1. The corresponding resolution ranges from 3.2 mm to 0.6 mm, and the corresponding transaxial field-of-view ranges from 84 mm to 10 mm. The sensitivity of the system varies from 220 cps/MBq to 340 cps/MBq for various configurations. Imaging of a mouse injected with a bone radiotracer revealed the finer structures that can be acquired at higher magnifications, and illustrated the ability to conveniently image with a variety of magnifications during the same study. In summary, we have brought the concept of an adaptive SPECT imaging system as it was originally described by Barrett et al. in 2008 to life. We have engineered a system that can switch configurations with speed, precision, and repeatability suitable to carry out adaptive imaging studies on small animals, thus opening the door to a new research and medical imaging paradigm in which the imager hardware is adjusted on the fly to maximize task-performance for a specific patient, not, as currently, an ensemble of patients.
Advisors/Committee Members: Furenlid, Lars R (advisor), Furenlid, Lars R. (committeemember), Barrett, Harrison H. (committeemember), Gmitro, Arthur F. (committeemember), Kupinski, Matthew A. (committeemember).
Subjects/Keywords: Optical Sciences
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APA (6th Edition):
Chaix, C. (2015). AdaptiSPECT: a Preclinical Imaging System
. (Doctoral Dissertation). University of Arizona. Retrieved from http://hdl.handle.net/10150/594908
Chicago Manual of Style (16th Edition):
Chaix, Cécile. “AdaptiSPECT: a Preclinical Imaging System
.” 2015. Doctoral Dissertation, University of Arizona. Accessed February 27, 2021.
http://hdl.handle.net/10150/594908.
MLA Handbook (7th Edition):
Chaix, Cécile. “AdaptiSPECT: a Preclinical Imaging System
.” 2015. Web. 27 Feb 2021.
Vancouver:
Chaix C. AdaptiSPECT: a Preclinical Imaging System
. [Internet] [Doctoral dissertation]. University of Arizona; 2015. [cited 2021 Feb 27].
Available from: http://hdl.handle.net/10150/594908.
Council of Science Editors:
Chaix C. AdaptiSPECT: a Preclinical Imaging System
. [Doctoral Dissertation]. University of Arizona; 2015. Available from: http://hdl.handle.net/10150/594908
University of Arizona
26.
Carlson, David R.
Frequency Combs for Spectroscopy in the Vacuum Ultraviolet
.
Degree: 2016, University of Arizona
URL: http://hdl.handle.net/10150/612874
► This dissertation explores frequency comb spectroscopy and, in particular, its extension to the vacuum-ultraviolet (VUV) and extreme-ultraviolet (XUV) wavelength regimes through a technique called intracavity…
(more)
▼ This dissertation explores frequency comb spectroscopy and, in particular, its extension to the vacuum-ultraviolet (VUV) and extreme-ultraviolet (XUV) wavelength regimes through a technique called intracavity high harmonic generation (IHHG). By combining the techniques of passive pulse amplification in an enhancement cavity with high harmonic generation, IHHG enables the direct conversion of near-infrared radiation to the VUV/XUV while still maintaining the underlying comb structure .As part of this work, a series of numerical simulations was performed to investigate the plasma that is formed in the IHHG process and its implications for the resulting VUV comb. It was demonstrated that a fundamental limitation to the performance of IHHG experiments is due to the single-pass ionization phase shift acquired by the pulse circulating in the enhancement cavity. Furthermore, we showed that a static background plasma accumulates between pulses and complicates cavity stabilization. Insights gained from the simulations led to the development of a novel pump-probe technique using the enhancement cavity that allowed a direct measurement of the intracavity plasma and its decay dynamics in real-time. Because the plasma lifetime plays such a crucial role in the operation of these cavities, it was important to have a method to test ways of reducing it. To build on our initial IHHG results showing record-level powers in the XUV, we implemented a fully phase-coherent dual comb spectrometer consisting of two identical IHHG systems operating in parallel. The system is designed for precision spectroscopy in the VUV and is based on a pair of homemade ytterbium fiber lasers that use a parabolic amplification scheme to achieve 80 fs pulses after amplification to 50 W of average power. Initial dual comb data showing system performance at the fundamental frequency and third harmonic are presented.
Advisors/Committee Members: Jones, Ronald Jason (advisor), Anderson, Brian P. (committeemember), Wright, Ewan M. (committeemember), Jones, Ronald Jason (committeemember).
Subjects/Keywords: Optical Sciences
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APA ·
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MLA ·
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Export
to Zotero / EndNote / Reference
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APA (6th Edition):
Carlson, D. R. (2016). Frequency Combs for Spectroscopy in the Vacuum Ultraviolet
. (Doctoral Dissertation). University of Arizona. Retrieved from http://hdl.handle.net/10150/612874
Chicago Manual of Style (16th Edition):
Carlson, David R. “Frequency Combs for Spectroscopy in the Vacuum Ultraviolet
.” 2016. Doctoral Dissertation, University of Arizona. Accessed February 27, 2021.
http://hdl.handle.net/10150/612874.
MLA Handbook (7th Edition):
Carlson, David R. “Frequency Combs for Spectroscopy in the Vacuum Ultraviolet
.” 2016. Web. 27 Feb 2021.
Vancouver:
Carlson DR. Frequency Combs for Spectroscopy in the Vacuum Ultraviolet
. [Internet] [Doctoral dissertation]. University of Arizona; 2016. [cited 2021 Feb 27].
Available from: http://hdl.handle.net/10150/612874.
Council of Science Editors:
Carlson DR. Frequency Combs for Spectroscopy in the Vacuum Ultraviolet
. [Doctoral Dissertation]. University of Arizona; 2016. Available from: http://hdl.handle.net/10150/612874
University of Arizona
27.
Roberts, Adam.
Time Domain Spectroscopy of Graphene
.
Degree: 2012, University of Arizona
URL: http://hdl.handle.net/10150/228120
► This dissertation describes the response of graphene and graphene fragments to ultrafast optical pulses. I will first describe how we created few-cycle optical pulses for…
(more)
▼ This dissertation describes the response of graphene and graphene fragments to ultrafast
optical pulses. I will first describe how we created few-cycle
optical pulses for interacting with the graphene lattice. These pulses are created through filamentation based pulse compression. I studied how the filamentation process can be optimized through simple means to create the shortest possible pulse. I then examine the extent to which graphene can withstand irradiation from intense ultra-fast pulses. I examine both the high intensity regime at which a single laser pulse will ablate the graphene and a more moderate regime that slowly degrades the graphene from long term exposure to ultrafast pulses. The knowledge lets us both identify a safe working regime for driving the graphene lattice with
optical fields as well as use ultrafast lasers to create graphene nano-fragments down to 2nm. Next, I explore the ultrafast dynamics of photo-excited graphene. Graphene undergoes electronic band renormalization after photo exciting carriers. By measuring a differential transmission spectrum, small changes to the band structure can be quantified. I will explain how screened exchange and electron phonon self energies provide corrections to the band structure for different times after carrier excitation. Lastly, I will describe measurements that determine the extent of electron-electron correlations in graphene fragments. By measuring the energy of the two photon state and comparing it the lowest energy one photon state in graphene fragments, we can determine the strength of the correlations in graphene systems.
Advisors/Committee Members: Sandhu, Arvinder (advisor), Jones, Jason (committeemember), Binder, Rolf (committeemember), Sandhu, Arvinder (committeemember).
Subjects/Keywords: Optical Sciences
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APA ·
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Manager
APA (6th Edition):
Roberts, A. (2012). Time Domain Spectroscopy of Graphene
. (Doctoral Dissertation). University of Arizona. Retrieved from http://hdl.handle.net/10150/228120
Chicago Manual of Style (16th Edition):
Roberts, Adam. “Time Domain Spectroscopy of Graphene
.” 2012. Doctoral Dissertation, University of Arizona. Accessed February 27, 2021.
http://hdl.handle.net/10150/228120.
MLA Handbook (7th Edition):
Roberts, Adam. “Time Domain Spectroscopy of Graphene
.” 2012. Web. 27 Feb 2021.
Vancouver:
Roberts A. Time Domain Spectroscopy of Graphene
. [Internet] [Doctoral dissertation]. University of Arizona; 2012. [cited 2021 Feb 27].
Available from: http://hdl.handle.net/10150/228120.
Council of Science Editors:
Roberts A. Time Domain Spectroscopy of Graphene
. [Doctoral Dissertation]. University of Arizona; 2012. Available from: http://hdl.handle.net/10150/228120
University of Arizona
28.
Wiersma, Joshua Thomas.
Pixelated Mask Polarization Based Spatial Carrier Interference Microscopy
.
Degree: 2012, University of Arizona
URL: http://hdl.handle.net/10150/265560
► The following dissertation demonstrates the advantages of using a camera with a pixelated polarization mask allowing spatial carrier phase shifting in interference microscopy. An interference…
(more)
▼ The following dissertation demonstrates the advantages of using a camera with a pixelated polarization mask allowing spatial carrier phase shifting in interference microscopy. An interference microscope in the Michelson and Linnik configurations integrates a camera equipped with a pixelated polarization mask. The camera utilizes polarization to simultaneously capture four phase shifted interferograms. Each set of four phase shifted fringe patterns permits the calculation of fringe contrast and phase at a point in the vertical scan of a test surface. The use of a short coherence source enables construction of a coarse surface profile by estimating the localization of the peak fringe contrast over the vertical scan. The coarse profile allows unwrapping of the less noisy, though circumstantially ambiguous, phase data. Established phase shifting interference microscopy methods utilize temporal phase shifting techniques. Temporal methods contrast spatial methods by acquiring each set of interferograms necessary for calculating fringe contrast and phase by scanning the test object. The scanning changes the
optical path difference between the interferometer arms thus inducing the phase shifts. While both methods scan the test surface, spatial methods acquire all of the information needed to calculate fringe contrast and phase simultaneously while the temporal methods require data from multiple points in the scan. Furthermore, the focus and fringe contrast also change between phase shifts and introduce a small error in temporal methods. However, the largest source of error results from the time taken between capturing the phase shifted frames comprising each set where environmental disturbances such as vibration can change the fringe pattern. The subsequent work shows the practicality of performing interference microscopy with a pixelated polarization mask as well as the technique's relative vibration insensitivity.
Advisors/Committee Members: Wyant, James (advisor), North-Morris, Michael (committeemember), Schwiegerling, James (committeemember), Wyant, James (committeemember).
Subjects/Keywords: Optical Sciences
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Export
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Manager
APA (6th Edition):
Wiersma, J. T. (2012). Pixelated Mask Polarization Based Spatial Carrier Interference Microscopy
. (Doctoral Dissertation). University of Arizona. Retrieved from http://hdl.handle.net/10150/265560
Chicago Manual of Style (16th Edition):
Wiersma, Joshua Thomas. “Pixelated Mask Polarization Based Spatial Carrier Interference Microscopy
.” 2012. Doctoral Dissertation, University of Arizona. Accessed February 27, 2021.
http://hdl.handle.net/10150/265560.
MLA Handbook (7th Edition):
Wiersma, Joshua Thomas. “Pixelated Mask Polarization Based Spatial Carrier Interference Microscopy
.” 2012. Web. 27 Feb 2021.
Vancouver:
Wiersma JT. Pixelated Mask Polarization Based Spatial Carrier Interference Microscopy
. [Internet] [Doctoral dissertation]. University of Arizona; 2012. [cited 2021 Feb 27].
Available from: http://hdl.handle.net/10150/265560.
Council of Science Editors:
Wiersma JT. Pixelated Mask Polarization Based Spatial Carrier Interference Microscopy
. [Doctoral Dissertation]. University of Arizona; 2012. Available from: http://hdl.handle.net/10150/265560
University of Arizona
29.
Smith, Paula Kay.
Characterizing Dielectric Tensors of Anisotropic Materials From a Single Measurement
.
Degree: 2013, University of Arizona
URL: http://hdl.handle.net/10150/293464
► Ellipsometry techniques look at changes in polarization states to measure optical properties of thin film materials. A beam reflected from a substrate measures the real…
(more)
▼ Ellipsometry techniques look at changes in polarization states to measure
optical properties of thin film materials. A beam reflected from a substrate measures the real and imaginary parts of the index of the material represented as n and k, respectively. Measuring the substrate at several angles gives additional information that can be used to measure multilayer thin film stacks. However, the outstanding problem in standard ellipsometry is that it uses a limited number of incident polarization states (s and p). This limits the technique to isotropic materials. The technique discussed in this paper extends the standard process to measure anisotropic materials by using a larger set of incident polarization states. By using a polarimeter to generate several incident polarization states and measure the polarization properties of the sample, ellipsometry can be performed on biaxial materials.Use of an optimization algorithm in conjunction with biaxial ellipsometry can more accurately determine the dielectric tensor of individual layers in multilayer structures. Biaxial ellipsometry is a technique that measures the dielectric tensors of a biaxial substrate, single-layer thin film, or multi-layer structure. The dielectric tensor of a biaxial material consists of the real and imaginary parts of the three orthogonal principal indices (nₓ + ikₓ, n(y) +ik(y) and n(z) + ik(z)) as well as three Euler angles (α, β, and γ) to describe its orientation. The method utilized in this work measures an angle-of-incidence Mueller matrix from a Mueller matrix imaging polarimeter equipped with a pair of microscope objectives that have low polarization properties. To accurately determine the dielectric tensors for multilayer samples, the angle-of-incidence Mueller matrix images are collected for multiple wavelengths. This is done in either a transmission mode or a reflection mode, each incorporates an appropriate dispersion model. Given approximate a priori knowledge of the dielectric tensor and film thickness, a Jones reflectivity matrix is calculated by solving Maxwell's equations at each surface. Converting the Jones matrix into a Mueller matrix provides a starting point for optimization. An optimization algorithm then finds the best fit dielectric tensor based on the measured angle-of-incidence Mueller matrix image. This process can be applied to polarizing materials, birefringent crystals and the multilayer structures of liquid crystal displays. In particular, the need for such accuracy in liquid crystal displays is growing as their applications in industry evolve.
Advisors/Committee Members: Chipman, Russell (advisor), Dereniak, Eustace (committeemember), Falco, Charles (committeemember), Chipman, Russell (committeemember).
Subjects/Keywords: Optical Sciences
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APA ·
Chicago ·
MLA ·
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CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Smith, P. K. (2013). Characterizing Dielectric Tensors of Anisotropic Materials From a Single Measurement
. (Doctoral Dissertation). University of Arizona. Retrieved from http://hdl.handle.net/10150/293464
Chicago Manual of Style (16th Edition):
Smith, Paula Kay. “Characterizing Dielectric Tensors of Anisotropic Materials From a Single Measurement
.” 2013. Doctoral Dissertation, University of Arizona. Accessed February 27, 2021.
http://hdl.handle.net/10150/293464.
MLA Handbook (7th Edition):
Smith, Paula Kay. “Characterizing Dielectric Tensors of Anisotropic Materials From a Single Measurement
.” 2013. Web. 27 Feb 2021.
Vancouver:
Smith PK. Characterizing Dielectric Tensors of Anisotropic Materials From a Single Measurement
. [Internet] [Doctoral dissertation]. University of Arizona; 2013. [cited 2021 Feb 27].
Available from: http://hdl.handle.net/10150/293464.
Council of Science Editors:
Smith PK. Characterizing Dielectric Tensors of Anisotropic Materials From a Single Measurement
. [Doctoral Dissertation]. University of Arizona; 2013. Available from: http://hdl.handle.net/10150/293464
University of Arizona
30.
Lau, Pick Chung.
Novel Applications of Semiconductor Nanocrystals
.
Degree: 2013, University of Arizona
URL: http://hdl.handle.net/10150/297024
► We have investigated ways of modifying a common water soluble CdTe NCs to become non-photobleaching. Such NCs are capable of responding reversibly to an inter-switching…
(more)
▼ We have investigated ways of modifying a common water soluble CdTe NCs to become non-photobleaching. Such NCs are capable of responding reversibly to an inter-switching of the oxygen and argon environments over multiple hours of photoexcitation. They are found to quench upon exposure to oxygen, but when the system is purged with argon, their photoluminescence (PL) revives to the original intensity. Such discovery could potentially be used as oxygen nanosensors. These PL robust CdTe NCs immobilized on glass substrates also exhibit significant changes in their PL when certain organic/bio molecules are placed in their vicinity (nanoscale). This novel technique also known as NC-organic molecule close proximity imaging (NC-cp imaging) has found to provide contrast ratio greater by a factor of 2-3 compared to conventional fluorescence imaging technique. PL of NCs is recoverable upon removal of these organic molecules, therefore validating these NCs as potential all-
optical organic molecular nanosensors and, upon optimization, ultimately serving as point detectors for purposes of super-resolution microscopy (with proper instrumentation). No solvents are required for this sensing mechanism since all solutions were dried under argon flow. Furthermore, core graded shell CdSe/CdSeₓS(1-x)/CdS giant nanocrystal (g-NCs) were found to have very robust PL temperature response. At a size of 10.2 nm in diameter, these g-NCs undergo PL drop of only 30% at 355K (normalized to PL intensity at 85K). In comparison, the core step shells CdSe/CdS g-NCs at the same diameter exhibit 80% PL drop at 355K. Spectral shifting and broadening were acquired and found to be 5-10 times and 2-4 times smaller respectively than the standard CdSe core and CdSe/CdS core shell NCs. It is also discovered that these core graded shell g-NCs are largely nonblinking and have insignificant photoluminescence decay even after exciting the samples at very high irradiance (44 kW/cm²) for over an hour. These types of g-NCs have great potential to be used as the active medium for temperature insensitive laser devices in the visible range or temperature insensitive bioprobes for bioimaging applications.
Advisors/Committee Members: Mansuripur, Masud (advisor), Norwood, Robert A. (committeemember), Peng, Leilei (committeemember), Mansuripur, Masud (committeemember).
Subjects/Keywords: Optical Sciences
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APA ·
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MLA ·
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CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Lau, P. C. (2013). Novel Applications of Semiconductor Nanocrystals
. (Doctoral Dissertation). University of Arizona. Retrieved from http://hdl.handle.net/10150/297024
Chicago Manual of Style (16th Edition):
Lau, Pick Chung. “Novel Applications of Semiconductor Nanocrystals
.” 2013. Doctoral Dissertation, University of Arizona. Accessed February 27, 2021.
http://hdl.handle.net/10150/297024.
MLA Handbook (7th Edition):
Lau, Pick Chung. “Novel Applications of Semiconductor Nanocrystals
.” 2013. Web. 27 Feb 2021.
Vancouver:
Lau PC. Novel Applications of Semiconductor Nanocrystals
. [Internet] [Doctoral dissertation]. University of Arizona; 2013. [cited 2021 Feb 27].
Available from: http://hdl.handle.net/10150/297024.
Council of Science Editors:
Lau PC. Novel Applications of Semiconductor Nanocrystals
. [Doctoral Dissertation]. University of Arizona; 2013. Available from: http://hdl.handle.net/10150/297024
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Open Access Theses and Dissertations
