Chinese Optics Letters, Vol. 18, Issue 10, 101201 (2020)
Low-frequency acoustic Fabry–Pérot fiber sensor based on a micromachined silicon nitride membrane
Zhiyuan Qu1, Ping Lu1,*, Yujian Li1, Xin Fu1, Wanjin Zhang1, Deming Liu1, and Jiangshan Zhang2
- 1Wuhan National Laboratory for Optoelectronics (WNLO) and National Engineering Laboratory for Next Generation Internet Access System, School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China
- 2Department of Electronics and Information Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
In this Letter, a low-frequency acoustic sensor based on an extrinsic Fabry–Pérot (FP) interferometer with a silicon nitride (Si3N4) membrane is demonstrated. Using micromachining techniques, the 800 nm thick Si3N4 membrane is deposited on an 8 mm × 8 mm × 400 μm silicon (Si) substrate. All the assembly procedures of the sensor are focused on the substrate to avoid any damage to the membrane itself, compared to general membrane transfer methods. The frequency response of the proposed sensor is discussed theoretically and experimentally demonstrated. The sensor exhibits an excellent flat response to the tested acoustic frequency range of 1 Hz to 250 Hz. The phase sensitivity is around ?152 dB re 1 rad/μPa with sensitivity fluctuation less than 0.8 dB. The frequency response characteristic shows a promising potential of the sensor in low-frequency acoustic signal sensing applications.
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