Optimization Investigations of Continuous Wave Cavity Ringdown Spectroscopy

Optimization investigations of continuous wave cavity ringdown spectroscopy have been analyzed by demonstrating the dynamic response of the ringdown cavity. The intensity variations of cavity reflection and transmission as functions of modulation frequency and intracavity absorption loss are researched theoretically and experimentally. The results indicate that a proper modulation frequency of cavity length should be chosen to ensure high signal-to-noise ratio of ringdown event and high data acquisition rate. Moreover, the cavity reflection is more superior, compared with cavity transmission, to create the trigger signal to optical switch for laser beam interruption. Finally, the reason of existed deviations between experimental and theoretical is discussed.