Tunable semiconductor laser with liquid crystal pixel mirror in grating-loaded external cavity

Abstract

A tunable semiconductor laser is developed by using a folded telescopic grating-loaded external cavity with a liquid crystal pixel mirror (LCPM) at the focal plane of the folded telescope. A narrow-band (<0.1 nm, instrument-limited) electrically tunable output from 636 to 643 nm in 0.27 nm steps with a low-power red laser diode (LD) in a commercial laser pointer is achieved. The sidemode suppression ratio (SMSR) of the laser output is better than 20 dB throughput this range. The tuning range and SMSR are limited by the reflectivity of the front facet of the LD and the contrast ratio of the LPCM.