Narrow-linewidth vertical-cavity surface-emitting lasers for oxygen detection.

The use of vertical-cavity surface-emitting lasers (VCSEL's) for optical detection of atmospheric oxygen is described. The VCSEL's were custom designed for single-mode emission in the 763-nm wavelength range, with low noise and narrow optical linewidth. Using standard wavelength modulation spectroscopy and a second-harmonic detection scheme with a 1-m air path, we determined an oxygen concentration resolution of 0.2%. Because of its small size, low power dissipation, and good tunability characteristics, the VCSEL promises to be an attractive light source for use in compact, low-cost optical sensor microsystems for trace gas detection.