Monolithic widely tunable laser diodes for gas sensing at 2100 nm

Novel monolithic widely tunable laser diodes in the 2.1 mu m wavelength region based on GaSb / AlGaAsSb are presented. Using the concept of a lateral binary superimposed (BSG) grating structures and multisegment Vernier-tuning, stable single-mode output is realized at discrete wavelength channels in the 2060 nm - 2140 nm region. A total tuning above 80 nm in six channels is demonstrated. In every wavelength channel, the output wavelength can be tuned by current and temperature. Each wavelength channel offers up to 6 nm of mode hop free tuning, making this novel widely tunable laser highly attractive as a monolithic light source for multiple-gas sensing or liquid detection purposes. The wavelength channels can be arbitrarily placed within the material gain allowing BSG lasers to sweep e.g. over several gas absorption line within 80 nm. Within a wavelength channel, the widely tunable lasers show DFB like spectral performance with average side-mode suppression-ratios above 40 dB, output power of up to 15 mW at 25 degrees C. Also temperature and current tuning coefficients are comparable to those of DFB lasers. This paper will present an overview of laser concept, performance data and applications.