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You searched for +publisher:"University of Wisconsin – Milwaukee" +contributor:("Arash Mafi"). Showing records 1 – 3 of 3 total matches.

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University of Wisconsin – Milwaukee

1. Gandomkar Yarandi, Parisa. High Power Gain Guided Index Antiguided Fiber Lasers and Amplifiers.

Degree: PhD, Engineering, 2013, University of Wisconsin – Milwaukee

Abstract Increasing the core size of high-power fiber lasers and amplifiers is highly desired in order to mitigate the unwanted nonlinear optical effects and raise the optical damage threshold. If the core size of conventional index-guided (IG) optical fibers increases, the fiber will become multimode, because it is very difficult to control and fine-tune the index step between the core and cladding to satisfy the single mode condition. Siegman proposed Gain-guided index-antiguided (GG-IAG) fibers as a possible platform for ultra-large-core single-mode operation for lasers and amplifiers. In this thesis, the beam-quality factor M2 for the fundamental LP01 mode of a step-index fiber with finite and infinite cladding diameter is calculated in the presence of gain as a function of the complex generalized V number. The numerical results agree with analytical work that obtained in our group. It is shown that the M2 value of a single-mode gain-guided fiber laser can be arbitrarily large. The results are important for the interpretation of the beam-quality measurements in recent experiments on single-mode gain-guided fiber lasers. It is also shown that the conventional infinite cladding diameter approximation cannot be used for index-antiguided gain-guided fibers, and the rigorous analysis is required for accurate prediction of the beam quality factor, as reported in recent experimental measurements. We also highlight the key reasons behind the poor power efficiency observed in multiple experiments in gain guided index-antiguided (GG-IAG) fiber amplifiers and lasers. We show that by properly designing the fiber geometrical characteristics, it is possible to considerably improve the power efficiency of GG-IAG fiber amplifiers in end-pumping schemes. Advisors/Committee Members: Arash Mafi.

Subjects/Keywords: Electrical and Electronics

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APA (6th Edition):

Gandomkar Yarandi, P. (2013). High Power Gain Guided Index Antiguided Fiber Lasers and Amplifiers. (Doctoral Dissertation). University of Wisconsin – Milwaukee. Retrieved from https://dc.uwm.edu/etd/249

Chicago Manual of Style (16th Edition):

Gandomkar Yarandi, Parisa. “High Power Gain Guided Index Antiguided Fiber Lasers and Amplifiers.” 2013. Doctoral Dissertation, University of Wisconsin – Milwaukee. Accessed July 14, 2020. https://dc.uwm.edu/etd/249.

MLA Handbook (7th Edition):

Gandomkar Yarandi, Parisa. “High Power Gain Guided Index Antiguided Fiber Lasers and Amplifiers.” 2013. Web. 14 Jul 2020.

Vancouver:

Gandomkar Yarandi P. High Power Gain Guided Index Antiguided Fiber Lasers and Amplifiers. [Internet] [Doctoral dissertation]. University of Wisconsin – Milwaukee; 2013. [cited 2020 Jul 14]. Available from: https://dc.uwm.edu/etd/249.

Council of Science Editors:

Gandomkar Yarandi P. High Power Gain Guided Index Antiguided Fiber Lasers and Amplifiers. [Doctoral Dissertation]. University of Wisconsin – Milwaukee; 2013. Available from: https://dc.uwm.edu/etd/249


University of Wisconsin – Milwaukee

2. Karbasivalashani, Salman. Transverse Anderson Localization in Disordered Optical Fibers.

Degree: PhD, Engineering, 2014, University of Wisconsin – Milwaukee

In any wave-guiding system, disorder and randomness in the wave propagation medium are considered as annoyances that result in wave scattering and inefficient wave transport. In contrast, in this work, the disorder is utilized in the transverse directions of an optical fiber for an effective light transport. The transversely disordered refractive index profile is invariant along the direction of propagation that results in transverse Anderson localization of light. A launched beam of light into the disordered fiber initially expands until it reaches the localization regime then propagates without further expansion in the transverse directions. A disordered polymer optical fiber composed of poly methyl methacrylate (PMMA) and poly styrene (PS) is designed using numerical simulations. The disordered polymer fiber is fabricated by drawing a preform of randomly mixed PMMA and PS strands. The light propagation in the disordered polymer fiber results in a localized beam radius that is comparable to the ones in the conventional optical fibers. The location of the transported beam at the output follows the location of the scanning beam at the input. In order to show the origin of transverse Anderson localization, the full vectorial modes of the disordered polymer optical fiber are calculated. The impacts of different design parameters on the light propagation in the disordered optical fibers are investigated. It is shown that the ultimate practical design is a disordered optical fiber that consists of glass and air sites with equal probability. The light propagation in a disordered glass optical fiber fabricated from porous glass with disordered air voids is studied as the first investigation of transverse Anderson localization in silica optical fibers. The non-uniform distribution of air voids in the glass host results in the wave localization in the regions with high fill-fraction of air voids. The possibility of simultaneous multiple-beam propagation in the disordered polymer optical fiber is examined numerically and experimentally. The impact of macro-bending on drifting the center of a propagating beam in the disordered polymer fiber is inspected. The macro-bending locally increases the refractive index difference between the disordered sites that results in a bend-insensitive wave propagation. The spatial multiplexing property of the disordered polymer fiber is utilized for high quality image transport. The quality of the transported images in the disordered polymer optical fiber is numerically and experimentally compared with the ones in the commercially available imaging fibers. The quality of the transported images is assessed using an effective objective evaluation technique. The impact of disorder on improving the image quality is specifically investigated by randomizing the radii of the cores in a periodic multicore fiber. Advisors/Committee Members: Arash Mafi.

Subjects/Keywords: Anderson Localization; Anderson Localized Optical Fibers; Disordered Fibers; Disordered Media; Image Transport; Optical Fibers; Electrical and Electronics

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APA (6th Edition):

Karbasivalashani, S. (2014). Transverse Anderson Localization in Disordered Optical Fibers. (Doctoral Dissertation). University of Wisconsin – Milwaukee. Retrieved from https://dc.uwm.edu/etd/464

Chicago Manual of Style (16th Edition):

Karbasivalashani, Salman. “Transverse Anderson Localization in Disordered Optical Fibers.” 2014. Doctoral Dissertation, University of Wisconsin – Milwaukee. Accessed July 14, 2020. https://dc.uwm.edu/etd/464.

MLA Handbook (7th Edition):

Karbasivalashani, Salman. “Transverse Anderson Localization in Disordered Optical Fibers.” 2014. Web. 14 Jul 2020.

Vancouver:

Karbasivalashani S. Transverse Anderson Localization in Disordered Optical Fibers. [Internet] [Doctoral dissertation]. University of Wisconsin – Milwaukee; 2014. [cited 2020 Jul 14]. Available from: https://dc.uwm.edu/etd/464.

Council of Science Editors:

Karbasivalashani S. Transverse Anderson Localization in Disordered Optical Fibers. [Doctoral Dissertation]. University of Wisconsin – Milwaukee; 2014. Available from: https://dc.uwm.edu/etd/464

3. Pourbeyram Kaleibar, Hamed. Nonlinear Processes in Multi-Mode Optical Fibers.

Degree: MS, Engineering, 2014, University of Wisconsin – Milwaukee

Nonlinear processes in optical fibers can affect data transmission and power carried by optical fibers and can limit the bandwidth and the capacity of optical communications. On the other hand nonlinear phenomena could be utilized to build in-fiber all-optical light sources and amplifiers. In this thesis new peaks inside an optical fiber have been generated using nonlinear processes. An intense green pump laser has been launched into a short fiber and specific modes have been excited to generate two new peaks in red and blue wavelengths, where two pump photons are annihilated to create two new photons in red and blue. The generated peaks are shifted far from pump; therefore they are less polluted by pump and Raman induced noises. The phase matching condition and the photon-flux rate for spontaneous and stimulated FWM have been studied both theoretically and experimentally for a commercial grade SMF-28 fiber. In low power and spontaneous regime new peaks are generated from quantum vacuum noise. Using the same pump laser for a long fiber, up to 21 new peaks spanning from green to Infrared have been generated. These peaks are equally spaced by 13THz. Generation of a Raman cascade spanning the wavelength range of 523 to 1750 nm wavelength range, in a standard telecommunication graded-index multimode optical fiber has been reported. Despite the highly multimode nature of the pump, the Raman peaks are generated in specific modes of the fiber, confirming substantial beam cleanup during the stimulated Raman scattering process. Advisors/Committee Members: Arash Mafi.

Subjects/Keywords: Four Wave Mixing; Multimode; Nonlinear; Optical Fiber; Raman Scattering; Engineering; Optics; Physics

…made it possible for me to accomplish this work. First, I deeply thank Professor Arash Mafi… 

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

APA (6th Edition):

Pourbeyram Kaleibar, H. (2014). Nonlinear Processes in Multi-Mode Optical Fibers. (Thesis). University of Wisconsin – Milwaukee. Retrieved from https://dc.uwm.edu/etd/481

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):

Pourbeyram Kaleibar, Hamed. “Nonlinear Processes in Multi-Mode Optical Fibers.” 2014. Thesis, University of Wisconsin – Milwaukee. Accessed July 14, 2020. https://dc.uwm.edu/etd/481.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Pourbeyram Kaleibar, Hamed. “Nonlinear Processes in Multi-Mode Optical Fibers.” 2014. Web. 14 Jul 2020.

Vancouver:

Pourbeyram Kaleibar H. Nonlinear Processes in Multi-Mode Optical Fibers. [Internet] [Thesis]. University of Wisconsin – Milwaukee; 2014. [cited 2020 Jul 14]. Available from: https://dc.uwm.edu/etd/481.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Pourbeyram Kaleibar H. Nonlinear Processes in Multi-Mode Optical Fibers. [Thesis]. University of Wisconsin – Milwaukee; 2014. Available from: https://dc.uwm.edu/etd/481

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

.