Cavity-enhanced Raman spectroscopy with optical feedback frequency-locking for gas sensing

A cavity-enhanced Raman spectroscopy (CERS) gas-sensing method is introduced. Using optical feedback frequency-locking, laser radiation provided by a diode laser is coupled into a three-mirror V-shaped optical cavity. An intracavity laser power of 92 W is realized, yielding a power gain factor of 2200. Raman spectrums of air, carbon dioxide, and acetylene are recorded as a demonstration. Multicomponent gas mixtures including isotopic gases can be simultaneously sensed by CERS. With 200 s exposure time, detection limits of 5.35 Pa for N-2, 5.07 Pa for O-2, 1.74 Pa for CO2, and 0.58 Pa for C2H2 are achieved. CERS is a powerful gas-sensing method with high selectivity and sensitivity, which also has the potential for quantitative analysis of gases with high accuracy. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement