Optical fiber micro-optical-electro-mechanical system ultrasonic sensor with composite film structure and manufacturing method thereof

Abstract

The invention discloses an optical fiber micro-optical-electro-mechanical system ultrasonic sensor with a composite film structure and a manufacturing method thereof. The composite film comprises a silicon nitride film and a silicon oxide film, the silicon oxide film grows on the upper surface of the silicon nitride film, and due to the difference of planar structures of the two films, the residual stress on the surface of the single-layer film can be effectively improved in the compounding process, and the sensitivity to ultrasonic waves is improved. According to the invention, the optical path differences of incident light with different wavelengths can be adjusted, the optical path differences of all wavelengths of broadband incident light can be kept consistent as a whole, stable optical interference can be realized, and the linear range of signal demodulation can be improved. By adopting the composite film structure, the response frequency range and the sound pressure intensity pressure bearing range of a sensitive diaphragm are improved, and the sensitive diaphragm can be applied to ultrasonic detection with wide bandwidth and high pressure intensity.

Description

technical field [0001] The invention belongs to the field of sensors, and in particular relates to an optical fiber micro-opto-electromechanical system ultrasonic sensor with a composite film structure and a manufacturing method thereof. Background technique [0002] Optical fiber micro-opto-electromechanical system acoustic wave sensing structure is an interdisciplinary field of optical fiber sensing technology and micro-opto-electromechanical system technology. Since the fiber optic ultrasonic technology was reported in the 1970s, it has anti-electromagnetic interference, is suitable for long-distance transmission, Significant advantages such as high sensitivity have received widespread attention. For acoustic wave measurement in a small space, strong corrosion, high voltage, and strong electromagnetic environment, the traditional electronic ultrasonic device cannot work normally. In this detection environment, the fiber optic acoustic wave sensor can transmit ultrasonic i...

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Problems solved by technology

[0003] However, in the prior art, there are the following disadvantages: 1. Residual stress generally exists in the manufacturing process of the single-structure sensing film, which greatly limits the response sensitivity; 2. The single-structure sensing film material cannot be sensitive to broadband The refractive index is adjusted by wide incident light, which causes the ultrasonic signal to be weakened, blanked or distorted, which is not conducive to the demodulation and analysis of the ultrasonic signal

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