High-power near-infrared QEPAS sensor for ppb-level acetylene detection using a 28 kHz quartz tuning fork and 10 W EDFA.

A high-power near-infrared (NIR) quartz enhanced photoacoustic spectroscopy (QEPAS) sensor for part per billion (ppb) level acetylene (CH) detection was reported. A 1536 nm distributed feedback (DFB) diode laser was used as the excitation light source. Cooperated with the laser, a C-band 10 W erbium-doped fiber amplifier (EDFA) was employed to boost the optical excitation power to improve QEPAS detection sensitivity. A pilot line manufactured quartz tuning fork (QTF) with a resonance frequency of 28 kHz was used as the photoacoustic transducer. In the case of high excitation power, gas flow effect and temperature effect were found and studied. Benefitting from the low QTF resonance frequency, high excitation power, and vibrational-translational (V-T) relaxation promoter, a detection limit of ∼7 ppb was achieved for CH detection, corresponding to a normalized noise equivalent absorption coefficient of 4.4×10cm · W · Hz.