Abstract
The ideal development direction of the fiber-optic acoustic sensor (FOAS) is toward broadband, a high sensitivity and a large dynamic range. In order to further promote the acoustic detection potential of the Fabry–Pérot etalon (FPE)-based FOAS, it is of great significance to study the acoustic performance of the FOAS with the quality (Q) factor of FPE as the research objective. This is because the Q factor represents the storage capability and loss characteristic of the FPE. The three FOASs with different Q factors all achieve a broadband response from 20 Hz to 70 kHz with a flatness of 2 dB, which is consistent with the theory that the frequency response of the FOAS is not affected by the Q factor. Moreover, the sensitivity of the FOAS is proportional to the Q factor. When the Q factor is , the sensitivity of the FOAS is as high as 526.8 mV/Pa. Meanwhile, the minimum detectable sound pressure of is achieved. Furthermore, with a Q factor of , the maximum detectable sound pressure and dynamic range are 152.32 dB and 107.2 dB, respectively, which is greatly improved compared with two other FOASs. Separately, the FOASs with different Q factors exhibit an excellent acoustic performance in weak sound detection and high sound pressure detection. Therefore, different acoustic detection requirements can be met by selecting the appropriate Q factor, which further broadens the application range and detection potential of FOASs.
Highlights
Received: 3 December 2021As a device of acoustic signal detection, the acoustic sensor is widely used in daily life and military, medical and aerospace fields, and has become an indispensable part of the development of modern society
Three Fabry–Pérot etalon (FPE) with different Q factors are selected as the core acoustic sensing elements of the fiber-optic acoustic sensor (FOAS), of which, the acoustic performances are theoretically analyzed and experimentally tested, respectively. It can be obtained from the experimental results that the frequency response range of the FOASs based on the FPEs with three different Q factors remains unchanged, which is from 20 Hz to 70 kHz with a flatness of
The sensitivity of the FOAS is proportional to the quality factor of FPE, and the ultrahigh sensitivity of 526.8 mV/Pa is achieved when the quality factor of FPE is 1.04 × 106
Summary
As a device of acoustic signal detection, the acoustic sensor is widely used in daily life and military, medical and aerospace fields, and has become an indispensable part of the development of modern society. The membrane-free FOAS based on FPE adopts a rigid structure of all glass, there is no mechanical displacement of the cavity length during the sensing process and a wide and flat frequency response range can be achieved. A high sound detection sensitivity can be realized by the FOAS based on the optical fiber and membrane They can only achieve a large bandwidth in water, and the bandwidth achieved in the air is average. It has been reported that the frequency response characteristics of the FOAS based on the membrane, which can realize a high sound pressure detection and high sensitivity, are not ideal. A membrane-free FOAS based on FPE can overcome the limitations of these acoustic sensors, and a wideband, high sensitivity and large dynamic range is achieved.
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