Near-infrared laser photoacoustic gas sensor for simultaneous detection of CO and H2S

A ppb-level H2S and CO photoacoustic spectroscopy (PAS) gas sensor was developed by using a two-stage commercial optical fiber amplifier with a full output power of 10 W. Two near-infrared diode lasers with the central wavenumbers of 6320.6 cm(-1) and 6377.4 cm(-1) were employed as the excitation laser source. A time-division multiplexing method was used to simultaneously detect CO and H2S with an optical switch. A dual-resonator structural photoacoustic cell (PAC) was theoretically simulated and designed with a finite element analysis. A mu V level background noise was achieved with the differential and symmetrical PAC. The performance of the multi-component sensor was evaluated after the optimization of frequency, pressure and modulation depth. The minimum detection limits of 31.7 ppb and 342.7 ppb were obtained for H2S and CO at atmospheric pressure. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Automated summary

A ppb-level H2S and CO photoacoustic spectroscopy gas sensor was developed using a two-stage commercial optical fiber amplifier with a full output power of 10 W. The sensor employed near-infrared diode lasers and a time-division multiplexing method for simultaneous detection. A dual-resonator structural photoacoustic cell was designed for achieving low background noise and minimum detection limits.