A novel photoacoustic spectroscopy system using diphragm based fiber Fabry-Perot sensor

A wavelength modulated photoacoustic spectroscopy system utilizing an optical fiber microphone and a tunable Erbium-doped fiber Ring laser combined with an erbium doped fiber amplifier is first developed. The diaphragm based Fabry-Perot sensor using interferometric/intensity demodulated method is used as high sensitive optical fiber microphone. This system is applied to the detection of acetylene using a resonant photoacoustic cell on its second longitudinal mode. The experimental results demonstrate that the low concentration acetylene flowing measurement can be detected by optical microphone, and the amplitude of second harmonic is proportion to the concentration of acetylene. The linearity is 0.9999. At room temperature and atmospheric pressure, the minimum detectable limit of acetylene is about 1.5 parts-per-billion (ppb) volume (SNR=1), which can be compared with condense microphone. (C) 2011 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of [CEIS 2011]