Near-IR tunable laser based photoacoustic sensor for sub-ppb C2H2 detections

摘要

A photoacoustic sensor for the detection of acetylene (C2H2) based on an EDFA-amplified tunable laser at 1530.37 nm is reported. This sensor consists of a near-IR tunable external cavity diode laser combined with a fiber amplifier and wavelength modulation mechanism. In order to improve detection sensitivity and accuracy, an optimized resonant photoacoustic cell based on an acoustic longitudinal mode and automatic tracking of the acoustic resonance frequency using a speaker and a FPGA-based servo controller is implemented. The minimum detection limit (signal-to-noise ratio = 1) of 0.8 ppb for C2H2 is demonstrated at room temperature and atmospheric pressure.