Abstract

Semiconductor diode lasers have been demonstrated as attractive sources for spectroscopic sensing applications because of their potential for narrow linewidths, ease of tuning and modulation, low operating powers and overall simplicity [1-4], In particular, vertical cavity surface emitting semiconductor lasers (VCSELs) have recently been demonstrated [l-4] to be particularly advantageous as sources for wavelength modulation/derivative spectroscopy. In this work, we describe the use of VCSELs for higher order derivative spectroscopy. In particular, using a 760 nm VCSEL with atmospheric oxygen, we have studied high order derivative spectra (up to the 8th order) for various lines in the A band, and also demonstrated enhanced signal-to-noise ratios and improved detection sensitivities. A minimum detectable absorbency of 6.58 × 10⁻⁶ has been demonstrated in this work; this detection sensitivity· represents an order of magnitude improvement over that reported previously [4].

© 1996 Optical Society of America