Air micro-cavity type fiber hydrophone, manufacturing method of the same, and signal detection method

Abstract

The invention discloses an air micro-cavity type fiber hydrophone, a manufacturing method of the same, and a signal detection method. The air micro-cavity type fiber hydrophone is formed by a fiber and an air micro-cavity at the end surface of the fiber, wherein the air micro-cavity can be used as a compressible Fabry-Perot cavity for sensing the micro-cavity length or reflected light interferencespectrum change caused by the external pressure so as to realize measurement of sound wave and ultrasonic wave. The manufacturing method of the air micro-cavity type fiber hydrophone is simple, and optically heats the fiber end surface coated with luminous absorption material to realize water vaporization on the fiber end surface and form an air micro-cavity on the fiber end surface, thus avoiding the complicated process, such as fiber Fabry-Perot cavity structure manufacturing and pressure sensitive film welding. Besides, the manufacturing method of the air micro-cavity type fiber hydrophonerealizes accurate on-line control of the cavity length by adjusting the heating laser power, can overcome the problem that a traditional manufacturing method is not enough in the repeatability of device structural parameters, can realize dynamic tuning of the measurement range and the working frequency band on single sensor, and can improve applicability of the sensor.

Description

technical field [0001] The invention relates to the technical field of pressure measuring devices, in particular to an air microcavity optical fiber hydrophone, a manufacturing method and a signal detection method. Background technique [0002] The optical fiber Fabry-Perot optical fiber sensor has simple structure and accurate detection. It is a common type of optical fiber hydrophone. When the elastic diaphragm in the Fabry-Perot cavity is on the diaphragm, the diaphragm will be deformed, thereby changing the cavity length of the Fabry-Perot cavity. By detecting the change of the reflected light interference spectrum caused by the change of the cavity length, it can be realized Measurement of sound waves and ultrasound. Therefore, at present most of the optical fiber Fabry-Perot hydrophones are based on the elastic diaphragm deformation caused by the detection pressure (invention patent CN103091013, "miniature SU-8 optical fiber Fabry-Perot pressure sensor and preparation...

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Problems solved by technology

Therefore, at present most of the optical fiber Fabry-Perot hydrophones are based on the elastic diaphragm deformation caused by the detection pressure (invention patent CN103091013, "miniature SU-8 optical fiber Fabry-Perot pressure sensor and preparation method"; invention patent CN101858809 , "An optical fiber Fabry-Perot pressure sensor and its preparation method"; invention patent CN102384809, "High-stability Fabry-Perot pressure sensor without glue packaging and its preparation method"). The process of making a hollow cavity on the end face of an optical fiber and bonding a membrane with a thickness of micron or even nanometer is relatively complicated and requires high process requirements; at the same time, due to the limitation of processing accuracy, the repeatability of structural parameters such as cavity length and film thickness of the sensor is difficult to obtain. Guarantee; on the other hand, the dynamic range and working frequency band of the traditional optical fiber pressure sensor depend on its structural parameters. Accurate detection of range signals, reducing sensor applicability and flexibility

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