A Compact and Efficient Frequency Stabilization System for 35 mW Visible Laser Diode with Real-Time Power Spectral Density Monitor

Shintaro HISATAKE  Yoshihiro KUROKAWA  Takahiro KAWAMOTO  Wakao SASAKI  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E85-C   No.1   pp.58-63
Publication Date: 2002/01/01
Online ISSN: 
DOI: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Recent Progress in Semiconductor Lasers and Light-Emitting Devices)
Category: 
Keyword: 
frequency stabilization,  linewidth reduction,  negative electrical feedback,  optical feedback,  visible laser diode,  

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Summary: 
We propose a frequency stabilization system for laser diodes (LD's), in which the major parameters in the stabilization process can be controlled in respond to the monitored frequency noise characteristics in real-time basis. The performance of this system was also tested through stabilizing a 35 mW visible LD. The center frequency of the LD has been stabilized by negative electrical feedback based on Pound-Drever-Hall technique. The linewidth of the LD has been reduced by adapting optical feedback from resonant confocal Fabry-Perot (CFP) cavity. The controlling parameters, especially gain levels and frequency responses of the negative electrical feedback loop can be manipulated to remove the instantaneous frequency noise by monitoring power spectral density (PSD) of the frequency error signals in the real-time basis. The achieved PSD of frequency noise of a sample LD stabilized by the present system was less than 1105 Hz2/Hz for the Fourier frequency < 10 MHz. The reduced linewidth was estimated to be narrower than 400 kHz. The achieved minimum square root of the Allan variance was 3.910-11 at τ = 0.1 msec.