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Title:Low threshold random lasing from phase separated optical fibers.
Author(s):Jagannathan, Srinath
Advisor(s):Dragic, Peter D
Department / Program:Electrical & Computer Eng
Discipline:Electrical & Computer Engr
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Random Lasers, Lasers, Fiber Lasers, Rayleigh scattering, Phase separation, Optical Amplifiers, and Laser Optics
Abstract:In this thesis, a low threshold novel random fiber laser, integrating a passive optical fiber with a phase separated aluminosilicate core – silica cladding as the feedback medium, is proposed and presented. The core exhibits greatly enhanced Rayleigh scattering, therefore requiring a significantly reduced length of scattering fiber (4 m) for lasing. The enhanced Rayleigh scattering was verified through measurements and a new figure of merit called effective power reflectivity was also developed to quantify random feedback. With a Yb-doped fiber as the gain medium, the fiber laser operates at 1050 nm with low threshold power, with a tractable lasing wavelength and maximum linewidth, and possesses an output that can be amplified through conventional means. Furthermore, the laser was found to have a high degree of spatial coherence, spectral broadening with increasing input power, and temporal spectral variation. The random lasing action was confirmed both by the use of RF beat spectra measurements and the trends in the Lévy exponent α obtained from the statistics of spectral intensity variation. Cutback experiments carried out shed light on the evolution of lasing behavior with P-SOF length and the impact of feedback on the lasing behavior. The minimum length of P-SOF required for maximum Rayleigh-distributed feedback was also determined to be ~ 2.5 m. This facile setup and results herein pave the way for further study and applications based on low threshold and compact random fiber lasers.
Issue Date:2020-07-22
Rights Information:Copyright 2020 Srinath Jagannathan
Date Available in IDEALS:2020-10-07
Date Deposited:2020-08

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