Opt Express. 2023 Feb 13;31(4):6974-6981. doi: 10.1364/OE.483240.
A sulfur dioxide (SO) gas sensor based on the photoacoustic spectroscopy technology in a sulfur hexafluoride (SF) gas matrix was demonstrated for SF decomposition components monitoring in the power system. A passive Q-switching laser diode (LD) pumped all-solid-state 266 nm deep-ultraviolet laser was exploited as the laser excitation source. The photoacoustic signal amplitude is linear related to the incident optical power, whereas, a random laser power jitter is inevitable since the immature laser manufacturing technology in UV spectral region. A compact laser power stabilization system was developed for better sensor performance by adopting a photodetector, a custom-made internal closed-loop feedback controller and a Bragg acousto-optic modulator (AOM). The out-power stability of 0.04% was achieved even though the original power stability was 0.41% for ∼ 2 hours. A differential two-resonator photoacoustic cell (PAC) was designed for weak photoacoustic signal detection. The special physical constants of SF buffer gas induced a high-Q factor of 85. A detection limit of 140 ppbv was obtained after the optimization, which corresponds to a normalized noise equivalent absorption coefficient of 3.2 × 10cmWHz.
基于光声光谱技术的二氧化硫（SO）气体传感器在六氟化硫（SF）气体基质中得到了证明，可用于监测电力系统中 SF 分解成分。采用被动调 Q 激光二极管（LD）泵浦的全固态 266nm 深紫外激光器作为激光激发源。光声信号幅度与入射光功率呈线性关系，然而，由于紫外光谱区域不成熟的激光制造技术，必然存在随机激光功率抖动。通过采用光电探测器、定制的内部闭环反馈控制器和布拉格声光调制器（AOM），开发了一种紧凑型激光功率稳定系统，以实现更好的传感器性能。即使原始功率稳定性为 0.41%，在大约 2 小时内也实现了 0.04%的输出功率稳定性。为了检测微弱的光声信号，设计了差分双共振腔光声池（PAC）。SF 缓冲气体的特殊物理常数导致 Q 因子高达 85。经过优化，得到了 140ppbv 的检测限，对应归一化噪声等效吸收系数为 3.2×10cmWHz。
