Study on narrow-frequency fiber-optic F-P acoustic wave sensor based on L-shaped spoke structure diaphragm
Fiber optic acoustic sensors are widely used in industry,medical and other fields.In order to improve the performance of fiber-optic Fabry-Perot acoustic sensors,a L-shaped spoke structure Fabry-Perot sensing diaphragm is proposed in this work.The thickness of the diaphragm is 15 μm,the width of the beam is 0.5 mm,and the radius of the center diaphragm is 1 mm.The diaphragm is etched on 304 stainless steel by laser processing technology.In the experiment,the sensitivity of the sensor at 1 000 Hz was investigated,and the sensor was applied to a photoacoustic spectroscopic gas detection system with a photoacoustic cell resonance frequency of 1 600 Hz,and measurement of acetylene(C2 H2)gas concentration from 50～100×10-6 was achieved.The experimental results indicate that the sound pressure sensitivity of the sensor is 25.4 nm/Pa at 1 000 Hz,the minimum detectable sound pressure(MDP)achievable by the sensor is 38.2 μPa/Hz1/2@1 kHz,and the acoustic pressure signal-to-noise ratio is 76.8 dB.The peak of the second harmonic signal of the photoacoustic spectroscopy obtained from the experiment shows a good linear relationship with the acetylene concentration,and the response of the acetylene concentration is 1.8 pm/10-6.The sensor has a wide range of applications in the field of single-frequency acoustic signal detection,such as photoacoustic spectroscopy.
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