Optical absorption spectroscopy based gas analyzer systems and methods

A gas analyzer system for measuring a concentration of a component in a gas mixture, the system comprising:

• a resonant optical cavity containing said gas and having at least two cavity mirrors, one of which is a cavity coupling mirror, wherein the resonant optical cavity defines a plurality of cavity modes having a free spectral range (FSR);
• a continuous-wave stepwise tunable external cavity laser emitting light optically coupled to the resonant optical cavity, wherein the external cavity laser comprises a semiconductor distributed feedback laser (DFB) as gain media and output coupler mirror forming a laser cavity;
• mode matching optics configured to couple the laser light to the resonant cavity via the cavity coupling mirror;
• a detector system for measuring an absorption of laser light by the gas in the resonant optical cavity, the detector system being operable to transmit a data signal corresponding to the absorption of laser light by the gas in the resonant optical cavity;
• and a processor operable to conduct the absorption spectroscopy analysis of the gas sample based on the data signal, wherein the ratio of the roundtrip optical cavity length of the external cavity laser to the roundtrip optical cavity length of the resonant cavity is between 0.8 and 1.2.