Transportable automated ammonia sensor based on a pulsed thermoelectrically cooled quantum-cascade distributed feedback laser

A compact ammonia sensor based on a 10-mum single-frequency, thermoelectrically cooled, pulsed quantum-cascade laser with an embedded distributed feedback structure has been developed. To measure NH3 concentrations, we scanned the laser over two absorption lines of its fundamental nu(2) band. A sensitivity of better than 0.3 parts per million was achieved with just a 1-m optical path length. The sensor is computer controlled and automated to monitor NH3 concentrations continuously for extended periods of time and to store data in the computer memory. (C) 2002 Optical Society of America.