Cavity-enhanced Raman spectroscopy for simultaneous detection of multiple gases using Pound-Drever-Hall technology

The accurate detection of multi-component gas is the key to realize the operation state assessment of gas insulated equipment. As a spectroscopy gas sensing method, Raman spectroscopy has the advantages of high selectivity, no cross-interference between different gases, and no consumption of samples. In this paper, a linear cavity enhanced Raman spectral detection platform based on PDH frequency locking technology is designed. A laser source (532 nm) is frequency locked to a linear resonator of finesse F = 391. Intracavity powers of 5 W are generated from 35mW of incident laser power, corresponding to a buildup factor of 140. With 60 s exposure time and 1 atm total pressure, the detection limits for gases
$(\mathrm{N}_{2}\ \mathrm{O}_{2})$
are 487.5
$\mu \mathbf{L}/\mathbf{L}$
and 443.2
$\mathbf{pL}/\mathbf{L}$
respectively, and with 30 s exposure time and 2 atm total pressure, the detection limit for SO
2
are 369.7
$\mu\mathbf{L}/\mathbf{L}$
.