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You searched for +publisher:"Clemson University" +contributor:("Dr. Eric G. Johnson, Committee Chair"). Showing records 1 – 2 of 2 total matches.

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Clemson University

1. Raghu Srimathi, Indumathi. Metaoptics for Spectral and Spatial Beam Manipulation.

Degree: PhD, Electrical and Computer Engineering, 2017, Clemson University

Laser beam combining and beam shaping are two important areas with applications in optical communications, high power lasers, and atmospheric propagation studies. In this dissertation, metaoptical elements have been developed for spectral and spatial beam shaping, and multiplexing. Beams carrying orbital angular momentum (OAM), referred to as optical vortices, have unique propagation properties. Optical vortex beams carrying different topological charges are orthogonal to each other and have low inter-modal crosstalk which allows for them to be (de)multiplexed. Efficient spatial (de)multiplexing of these beams have been carried out by using diffractive optical geometrical coordinate transformation elements. The spatial beam combining technique shown here is advantageous because the efficiency of the system is not dependent on the number of OAM states being combined. The system is capable of generating coaxially propagating beams in the far-field and the beams generated can either be incoherently or coherently multiplexed with applications in power scaling and dynamic intensity profile manipulations. Spectral beam combining can also be achieved with the coordinate transformation elements. The different wavelengths emitted by fiber sources can be spatially overlapped in the far-field plane and the generated beams are Bessel-Gauss in nature with enhanced depth of focus properties. Unique system responses and beam shapes in the far-field can be realized by controlling amplitude, phase, and polarization at the micro-scale. This has been achieved by spatially varying the structural parameters at the subwavelength scale and is analogous to local modification of material properties. With advancements in fabrication technology, it is possible to control not just the lithographic process, but also the deposition process. In this work, a unique combination of spatial structure variations in conjunction with the conformal coating properties of an atomic layer deposition tool has been utilized to create metal-oxide nano-hair structures that are compatible with high power laser systems. These devices are multifunctional – acting as resonant structures for one wavelength regime and as effective index structures in a different wavelength regime. Discrete and continuous phase functions have been realized with this controlled fabrication process. The design, simulation, fabrication and experimental characterization of these optical elements are presented. Advisors/Committee Members: Dr. Eric G. Johnson, Committee Chair, Dr. Richard J. Watkins, Dr. Goutam Koley, Dr. Lin Zhu.

Subjects/Keywords: Diffractive Optics; Orbital Angular Momentum; Spatial Demultiplexing; Spatial Multiplexing; Spectral Beam Combining; Subwavelength Grating Structures

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Raghu Srimathi, I. (2017). Metaoptics for Spectral and Spatial Beam Manipulation. (Doctoral Dissertation). Clemson University. Retrieved from https://tigerprints.clemson.edu/all_dissertations/1933

Chicago Manual of Style (16th Edition):

Raghu Srimathi, Indumathi. “Metaoptics for Spectral and Spatial Beam Manipulation.” 2017. Doctoral Dissertation, Clemson University. Accessed September 18, 2020. https://tigerprints.clemson.edu/all_dissertations/1933.

MLA Handbook (7th Edition):

Raghu Srimathi, Indumathi. “Metaoptics for Spectral and Spatial Beam Manipulation.” 2017. Web. 18 Sep 2020.

Vancouver:

Raghu Srimathi I. Metaoptics for Spectral and Spatial Beam Manipulation. [Internet] [Doctoral dissertation]. Clemson University; 2017. [cited 2020 Sep 18]. Available from: https://tigerprints.clemson.edu/all_dissertations/1933.

Council of Science Editors:

Raghu Srimathi I. Metaoptics for Spectral and Spatial Beam Manipulation. [Doctoral Dissertation]. Clemson University; 2017. Available from: https://tigerprints.clemson.edu/all_dissertations/1933


Clemson University

2. Li, Yuan. Study on the Amplification of Spatial Modes in a Crystal Rod Amplifier.

Degree: PhD, Electrical Engineering, 2016, Clemson University

In this work, the amplification of higher order modes, mainly focused on optical vortices that carry orbital angular momentum (OAM), were demonstrated and discussed in a Ho:YAG rod amplifier and Ho:YAG single crystal fiber (SCF) amplifier at 2 μm. Both experiments and simulations were carried out to understand the propagation, amplification and phase preservation of optical vortices in solid state amplifiers. A 3-D propagation model combining semi-vectorial BPM and steady state rate equations was used to verify the experimental results and to simulate the high power amplification. The amplification of optical vortices was experimentally demonstrated in a Ho:YAG rod amplifier for both – the case of incoherently multiplexed seeds and the case of coherently multiplexed seeds. A matched filter was used to evaluate the phase of the amplified seed beams and it is proven that the important phase information of the seeds was preserved through the amplification process. Pump beam profile engineering is also discussed for optimizing the gain for a desired seed beam. The amplification of optical vortices were also demonstrated in a Ho:YAG SCF amplifier. The SCF has a small diameter and a large surface-to-volume ratio to ensure guidance for both pump and seed beams. The optical spectroscopic properties, small signal gain and lasing characteristics of the Ho:YAG SCF were investigated. Then the amplification of higher order vortices was demonstrated in the SCF as well. The high power operation potential of the SCF amplifier is also discussed together with the associated thermal issues. With improved SCF fabrication techniques, SCF exhibits great potential to function as a high power multimode amplifier. Advisors/Committee Members: Dr. Eric G. Johnson, Committee Chair, Dr. John Ballato, Dr. Liang Dong, Dr. Joe Watkins, Dr. Lin Zhu.

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Li, Y. (2016). Study on the Amplification of Spatial Modes in a Crystal Rod Amplifier. (Doctoral Dissertation). Clemson University. Retrieved from https://tigerprints.clemson.edu/all_dissertations/1834

Chicago Manual of Style (16th Edition):

Li, Yuan. “Study on the Amplification of Spatial Modes in a Crystal Rod Amplifier.” 2016. Doctoral Dissertation, Clemson University. Accessed September 18, 2020. https://tigerprints.clemson.edu/all_dissertations/1834.

MLA Handbook (7th Edition):

Li, Yuan. “Study on the Amplification of Spatial Modes in a Crystal Rod Amplifier.” 2016. Web. 18 Sep 2020.

Vancouver:

Li Y. Study on the Amplification of Spatial Modes in a Crystal Rod Amplifier. [Internet] [Doctoral dissertation]. Clemson University; 2016. [cited 2020 Sep 18]. Available from: https://tigerprints.clemson.edu/all_dissertations/1834.

Council of Science Editors:

Li Y. Study on the Amplification of Spatial Modes in a Crystal Rod Amplifier. [Doctoral Dissertation]. Clemson University; 2016. Available from: https://tigerprints.clemson.edu/all_dissertations/1834

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