Trace Methane Detection Based on Raman Spectroscopy Using a High Finesse Optical Resonator

Abstract

A Raman spectroscopy-based gas sensor employing a high-finesse simple diode laser pumped external cavity, Power Build-up Cavity (PBC), has been developed. Results show that a compact 10-cm-long PBC includes a simple diode-laser-pumped external cavity could achieve an intra-cavity power of 40 W with a photon lifetime of up to 29 μs. Raman scattering light from trace methane in the PBC was detected by a photo multiplier tube and a bandpass filter. Good linearity of the detected Raman signal was obtained in the 90-500 ppm methane concentration region with a response time of 1 sec.