Influence of temperature-induced cavity length variation in wavelength modulation spectroscopy

The long-term stability of a given concentration of detected gas in laser spectroscopy is always difficult to achieve. We propose that the optical fringe shift caused by temperature-induced cavity length change is the most important factor that limits long-term stability. A wide range of temperature variation causes a large fluctuation in the detected concentration for a long period, and cavities made of a low-temperature expansion material can effectively inhibit the effects of a large temperature variation and improve the minimum detection limit.