Abstract

In recent years there has been considerable interest in using diode laser based sensors for a variety of gas monitoring applications in different environments. Tunable diode lasers (TDLs) have the advantages of low power consumption, small size, non-intrusiveness, high speed modulation, and ease of use. One spectroscopic technique that has been employed with diode lasers to obtain high detection sensitivity is frequency modulation spectroscopy (FMS).^1-5 The technique has been used for quantum limited detection of absorbances at the 10⁻⁸ level. TDLs are ideal candidates for FMS since they can be easily modulated at high frequencies by direct injection current modulation.

© 1994 Optical Society of America