APPLICATION OF BALANCED DETECTION TO ABSORPTION MEASUREMENTS OF TRACE GASES WITH ROOM-TEMPERATURE, QUASI-CW QC LASERS

Distributed feedback quantum cascade (QC) lasers are expected to form the heart of the next generation mid-IR laser absorption spectrometer, especially as applied to measurements of trace gases in a variety of environments. Incorporation of room temperature-operable, single mode QC lasers will result in very compact and rugged sensors for real world applications. We report preliminary results on the performance of a laser absorption spectrometer using a QC laser operating at room temperature in quasi-cw mode in conjunction with balanced ratiometric detection. We have demonstrated sensitivities for N2O (10 parts in 10 6 for a 1 m path (ppmv-m)) and NO (520 parts in 10 for a 1 m path (ppbv-m)) at 5.4 μm. System improvements are described which are expected to result in two orders of magnitude increase in sensitivity. OCIS codes: 010.1120, 120.1740, 140.3070, 300.1030, 300.6260

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