Chirped Grating Tunable Lasers for the Infrared Molecular Fingerprint Spectral Region
Technical rept. 21 Jul 2010-30 Apr 2012
NEW MEXICO UNIV ALBUQUERQUE OFFICE OF THE VICE PROVOST FOR RESEARCH
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A new approach approach to tunable mid-infrared lasers, an optically pumped, type-II, InGaSbInAs gain medium with a chirped distributed feedback grating, has been developed. The chirped grating is patterned using an interferometric lithography IL technique with spherical wave fronts and etched into the top cladding of the laser slab waveguide structure. A reduced longitudinal chirp grating fabrication technique has been developed that dramatically extends the single frequency tuning range. Continuous tuning of 80nm around 3.1 um with 320 mW single facet output power at 80K and a 1.6nm FWHM is reported. The present device is designed in the 3-to-4 um range which matches a low loss atmospheric transmission window, and covers an important region of molecular vibration spectra, in particular, the hydrocarbon C-H stretch at 3.3 um, making it suitable for atmospheric pressure remote gas sensing of industrially important small molecules such as methane, hydrogen chloride an ammonia.
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