Advanced search options

Advanced Search Options 🞨

Browse by author name (“Author name starts with…”).

Find ETDs with:

in
/  
in
/  
in
/  
in

Written in Published in Earliest date Latest date

Sorted by

Results per page:

Sorted by: relevance · author · university · dateNew search

You searched for subject:(far field beam). Showing records 1 – 2 of 2 total matches.

Search Limiters

Last 2 Years | English Only

No search limiters apply to these results.

▼ Search Limiters


University of Oklahoma

1. Rassel, SM Shazzad. CHARACTERIZATION AND DEVELOPMENT OF SEMICONDUCTOR CASCADE DEVICES.

Degree: PhD, 2018, University of Oklahoma

Interband cascade lasers (ICLs) are efficient source of mid-infrared light for many applications that require low power consumption and continuous wave (cw) operation at room temperature. In the last decade, remarkable progress has been made in developing ICLs on GaSb substrates, mainly in the 3 to 4μm wavelength region, but room temperature (RT) cw operation at the longer wavelength region beyond 6μm has not been achieved. Based on the characterization of earlier grown ICLs, InAs-based plasmon-waveguide ICLs were designed and fabricated to achieve improved performance near or beyond 6μm. These lasers were extensively characterized, investigated and analyzed in terms of various performance features and compared to other state-of-the-art lasers. One laser demonstrated a threshold current density (Jth) as low as 333A/cm2 at 300K for emission at 6003nm. This Jth is the lowest ever reported for a mid-infrared semiconductor laser in this wavelength range. These ICLs lased at temperatures up to 293K in cw mode and up to 357K in pulsed mode. A narrow-ridge laser operated in cw at 293K with a threshold input power as low as 0.66W, and was able to generate 3mW/facet output power at 280K, without accounting for beam divergence loss. These results are very encouraging examples of efficient ICLs at long wavelengths with low power consumption. To investigate the quality of the laser beam of these InAs-based ICLs, the far-field patterns were studied and analyzed for both broad-area and narrow-ridge geometries. In the growth direction, near diffraction-limited single-mode beams were obtained. As expected, multi-mode lasing was observed in the lateral direction because the stripe widths were much longer than the lasing wavelength. Also, as expected, these multi-modes were found to be dependent on applied bias current. These far-field profiles were compared to simulations and reasonable agreement was obtained. Beam propagation factors were plotted against the laser stripe sizes and the values were found close to unity along the growth direction -indicating better beam quality, and below 18 along lateral direction -indicating room for improvement. This methodology can be applied to previously fabricated ICLs to better understand their beam optics. In a related research project, single mode operation of ICLs was obtained by designing and fabricating a cleaved-coupled-cavity (CCC) laser. In our case, rather than cleaving to fabricate two cavities, we successfully demonstrated two ion-milling recipes, using a focused ion beam (FIB) to fabricate our CCC lasers. One recipe separated the two sections of CCC lasers electrically and the other recipe milled a narrow slot (air-gap) into the mesa. Based on the optical power from the fabricated cavities, the quality of the milled facet was found to be comparable to that of an as-cleaved facet. This CCC laser demonstrated a single mode operation at ~3109nm at room temperature with a reasonable side-mode-suppression-ratio (SMSR) of 24dB. A continuous tuning range of ~1.1nm and… Advisors/Committee Members: Yang, Rui (advisor), Johnson, Matthew (committee member), Santos, Michael (committee member), Sigmarsson, Hjalti (committee member), Fulton, Caleb (committee member).

Subjects/Keywords: interband cascade laser; high-frequency; coupled cavity laser; far field beam; carrier transport

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

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

APA (6th Edition):

Rassel, S. S. (2018). CHARACTERIZATION AND DEVELOPMENT OF SEMICONDUCTOR CASCADE DEVICES. (Doctoral Dissertation). University of Oklahoma. Retrieved from http://hdl.handle.net/11244/299799

Chicago Manual of Style (16th Edition):

Rassel, SM Shazzad. “CHARACTERIZATION AND DEVELOPMENT OF SEMICONDUCTOR CASCADE DEVICES.” 2018. Doctoral Dissertation, University of Oklahoma. Accessed March 07, 2021. http://hdl.handle.net/11244/299799.

MLA Handbook (7th Edition):

Rassel, SM Shazzad. “CHARACTERIZATION AND DEVELOPMENT OF SEMICONDUCTOR CASCADE DEVICES.” 2018. Web. 07 Mar 2021.

Vancouver:

Rassel SS. CHARACTERIZATION AND DEVELOPMENT OF SEMICONDUCTOR CASCADE DEVICES. [Internet] [Doctoral dissertation]. University of Oklahoma; 2018. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/11244/299799.

Council of Science Editors:

Rassel SS. CHARACTERIZATION AND DEVELOPMENT OF SEMICONDUCTOR CASCADE DEVICES. [Doctoral Dissertation]. University of Oklahoma; 2018. Available from: http://hdl.handle.net/11244/299799


University of Dayton

2. Han, Wei. Transmissive beam steering through Electrowetting Microprism arrays.

Degree: MS(M.S.), Electro-Optics, 2009, University of Dayton

In this study, the electrowetting phenomenon is reviewed and two types of Electrowetting Microprism (EMP) beam steering devices are proposed and theoretically characterized: single-prism and bi-prism EMP arrays. For this thesis, an extended beam propagation method is used and numerical calculations of near-field and far-field intensities are performed for both designs. I investigated both one-dimensional and two-dimensional versions of the EMP arrays and determine the beam steering efficiency for both 1D and 2D cases using an incident Gaussian beam. For the phased arrays the diffraction angles are discrete due to the well known grating effect. The angles between the diffraction peaks can be covered by applying a tilted phase to the input field. The efficiency is measured over continuously changed far-field angles for different situations. Advisors/Committee Members: Haus, Joseph W. (Committee Chair).

Subjects/Keywords: Optics; Beam steering; Electrowetting microprism; Far-field diffraction efficiency

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

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

APA (6th Edition):

Han, W. (2009). Transmissive beam steering through Electrowetting Microprism arrays. (Masters Thesis). University of Dayton. Retrieved from http://rave.ohiolink.edu/etdc/view?acc_num=dayton1262130475

Chicago Manual of Style (16th Edition):

Han, Wei. “Transmissive beam steering through Electrowetting Microprism arrays.” 2009. Masters Thesis, University of Dayton. Accessed March 07, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1262130475.

MLA Handbook (7th Edition):

Han, Wei. “Transmissive beam steering through Electrowetting Microprism arrays.” 2009. Web. 07 Mar 2021.

Vancouver:

Han W. Transmissive beam steering through Electrowetting Microprism arrays. [Internet] [Masters thesis]. University of Dayton; 2009. [cited 2021 Mar 07]. Available from: http://rave.ohiolink.edu/etdc/view?acc_num=dayton1262130475.

Council of Science Editors:

Han W. Transmissive beam steering through Electrowetting Microprism arrays. [Masters Thesis]. University of Dayton; 2009. Available from: http://rave.ohiolink.edu/etdc/view?acc_num=dayton1262130475

.