Mid-infrared gas detection using optically immersed, room-temperature, semiconductor devices

Abstract

We report the application of optically immersed, room-temperature InSb/InAlSb LED and photodiode devices to the ppm-level detection of nitrogen dioxide (NO2) at a wavelength of 6 µm. The LED emission and the photodiode detectivity are both increased by the optical immersion, resulting in a power dissipation of only 0.25 mW in the LED. A White cell is used for high gas sensitivity and its relatively small numerical aperture can be conveniently matched to the field of view of the hyperspherically immersed devices.