A 4.26-μm RCLED and a fast low-power CO 2 sensor

We have developed 4.26 μm room temperature resonant-cavity light-emitting diodes (RCLED) using III-V material system (InAs, InSb, and GaSb). The emission spectrum of RCLED closely matches the CO2 absorption profile. The wavelength of the peak of the emission spectrum is stable with respect to wide variations in the temperature and the drive current. Consequently we were able to develop a low cost RCLED based CO2 sensor operating over a wide temperature ranges of +5 to + 45 degrees C and minus 20 to + 60 degrees C (depending on the IR detector used) without a TE-cooler. These sensor devices consume very low power, at the level of mW, with a fast response time of 10 sec and better. It can measure CO2 levels in the range 0-10,000ppm with an accuracy of better than +-5%.