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 Title: Single frequency semiconductor lasers Author(s): Smith, Gary Michael Doctoral Committee Chair(s): Coleman, James J. Department / Program: Electrical and Computer Engineering Discipline: Electrical Engineering Degree Granting Institution: University of Illinois at Urbana-Champaign Degree: Ph.D. Genre: Dissertation Subject(s): Engineering, Electronics and Electrical Physics, Optics Engineering, Materials Science Abstract: Single frequency semiconductor lasers are of interest for communication systems and spectroscopy. In communications, narrow linewidth is desirable to minimize dispersion effects and low cross-talk multiple wavelength channels on a single fiber. For GaAs-based lasers, the interest in narrow linewidth sources comes from the spectroscopy community that desires a light source that can be tuned to very narrow absorption spectra of various materials. For both of these applications, narrow linewidth, wavelength tunable semiconductor lasers are well-suited.This thesis describes the development of a single epitaxial growth ridge waveguide distributed Bragg reflector (RW-DBR) laser. These lasers exhibit low thresholds, fairly high slope efficiencies, and single frequency operation with very narrow linewidth. The fabrication requires only a single epitaxial growth of a standard laser structure and then an anisotropic etch to transfer a grating pattern from the top surface of the laser into the epitaxial layers. The initial RW-DBR lasers fabricated by this method had symmetric cladding layers with a thickness of 1.2 $\mu$m, which required etch depths of over 1 $\mu$m in order to couple adequately to the optical mode. This required a highly anisotropic etch and limited the device design to third-order gratings. However, fairly good device performance was demonstrated with these symmetric cladding RW-DBR lasers.To relax the constraints on the grating etch, an asymmetric cladding separate confinement heterostructure (AC-SCH) laser was developed. The AC-SCH design reduces the thickness of the top cladding layer, which results in shallower depths for the grating etch and allows the fabrication of more efficient second-order DBR gratings. The incorporation of the AC-SCH into the RW-DBR laser reduces the threshold current, increases the efficiency, and decreases the spectral linewidth. Issue Date: 1996 Type: Text Language: English URI: http://hdl.handle.net/2142/19117 Rights Information: Copyright 1996 Smith, Gary Michael Date Available in IDEALS: 2011-05-07 Identifier in Online Catalog: AAI9625195 OCLC Identifier: (UMI)AAI9625195
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