Tunable-diode-laser spectroscopy of C_(2)H_(2) using a 3.03 (mu)m GaInAsSb/AlGaInAsSb distributed-feedback laser

摘要

The mid-IR region beyond 3 (mu)m is very attractive for gas sensing, since the fundamental absorption bands of several hydrocarbons are located in this range. We demonstrated, for the first time to our knowledge, the use of a novel GaInAsSb/AlGaInAsSb distributed-feedback laser emitting around 3.03 (mu)m in a tunable-diode laser-spectroscopy application. The laser operates in continuous mode at room temperature with excellent single-mode and tuning properties. A comparison of the measurement results was made with the recently updated data on ~(12)C_(2)H_(2) found in the HITRAN 2008 compilation. A good agreement was found between the measurements and the database. Wavelength modulation spectroscopy of acetylene at ambient conditions was made, and a sensitivity of 18 ppb (parts per billion) per meter at an integration time of 3 s corresponding to a relative absorption of 5 X 10~(-6) was obtained. The optimum detection limit of the acetylene measurement in this wavelength modulation spectroscopy setup was better than 1.5 ppb m at an integration time of 600 seconds.