Abstract

A novel tunable diode laser spectrometer operating at 8 < λ < 28 μm is described. A blocked impurity band Si:As chip is employed as detector. This device operates in this wavelength range with high detectivity and adequate frequency response for the high-sensitivity techniques used. A combination of sweep averaging and second-harmonic detection at 22 kHz yielded signal-to-noise ratios of 1200 at λ > 20 μm. The sensitivity and spectral resolution achieved are 1 order of magnitude better than those of Fourier instruments in this range, with an improvement in instrument time response of ~3000. Several molecular bands of CO₂ and N₂O are observed for what is, to our knowledge, the first time with this instrument. Examples of spectral line measurements are presented.

© 1993 Optical Society of America

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