Quantum cascade lasers for sensing applications

摘要

Modern gas sensor systems based on tunable diode laser spectroscopy (TDLS) have shown to reach impressive detection limits as low as a few ppb [1] and have proven their reliability for trace gas analysis at sophisticated sensitivities. Key elements of these systems are distributed feedback lasers operating in the near infrared regime. The TDLS technique is based on tuning the laser emission across absorption lines of the molecules to be detected while the degree of laser absorption serves as a measure of the gas concentration as well as the partial pressure of the gas species under investigation. Typically the absorption probability of many technologically and ecologically relevant gases increases drastically with wavelength [2].