Abstract
We report studies of Pb1−xSnxTe and Pb1−xGex Te laser characteristics which affect their performance in high-sensitivity gas analysis. In Pb1−xSnxTe, the rates at which the energy gap Eg and the individual cavity mode frequencies tune with current are consistent with published data. Single-mode operation typically occurs near threshold; at higher currents, multimode operation is common. In Pb1−xGexTe, Eg and tune more slowly, and multimode operation generally occurs. High-resolution absorption measurements on C2H4 (950 cm−1) and NH3 (931 cm−1) indicate that the frequency reproducibility of the lasers is adequate for trace gas analysis. Such analysis has been performed on calibrated samples of C2H4 in N2 at atmospheric pressure. The minimum detectable C2H4 concentration for a 10-cm path was between 17 ppm and 50 ppm, in good agreement with the 30 ppm estimated for detector-noise-limited operation. Effects of detector and laser noise on detection sensitivity are discussed.
© 1976 Optical Society of America
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