Please use this identifier to cite or link to this item:
http://hdl.handle.net/11375/25172
Title: | Broad-Band Antireflection Coatings for Improved Grating-External-Cavity Diode Laser Performance |
Authors: | Guo, Liqiang |
Advisor: | Cassidy, D. T. Mascher, P. |
Department: | Engineering Physics |
Keywords: | broad-band antireflection coatings;diode laser |
Publication Date: | Aug-2002 |
Abstract: | In this thesis, strong optical feedback is utilized to realize broad-band wavelength tuning and to stabilize the frequency of a semiconductor diode laser in a grating-external-cavity (GEC) configuration. To reach the regime of strong optical feedback, the laser facet through which the feedback occurs has to be antireflection (AR) coated. Multi-layer AR coatings were designed using SiO2, Si3N4, SiOxNy, and a:Si for specific laser waveguide structures, and were fabricated by an electron cyclotron resonance, plasma enhanced, chemical vapor deposition (ECR-PECVD) system. The film thickness and refractive index were monitored by in situ ellipsometry during the deposition. This scheme permitted very low reflectivities, in the order of 5 x 10-4, to be readily and reproducibly obtained. The diode laser thus obtained was used in a strong feedback configuration. Light emitted from the coated facet was collimated and fed back onto the laser cavity after being reflected off a diffraction grating. The diffraction grating provides frequency selectivity, which is a desirable feature for obtaining a stable single longitudinal mode laser. The laser in this configuration oscillated in a single mode with a greater than 30 dB side mode suppression ratio and a wide tuning range. |
URI: | http://hdl.handle.net/11375/25172 |
Appears in Collections: | Digitized Open Access Dissertations and Theses |
Files in This Item:
File | Description | Size | Format | |
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Guo_Liqiang_2002Aug_masters.pdf.pdf | 5.12 MB | Adobe PDF | View/Open |
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