Optical fiber hydrophone adopting reflective quasi-reciprocity optical path

Abstract

The invention belongs the technical field of optical fiber sensing, and particularly discloses an optical fiber hydrophone adopting a reflective quasi-reciprocity optical path. The optical fiber hydrophone comprises a light source, a shunt, a polarizer, a phase modulator, a delay optical fiber, a faraday rotator, an acoustic probe, a compensated optical fiber, a reflector and a photoelectric detector. The invention provides the optical fiber hydrophone adopting the reflective quasi-reciprocity optical path, can effectively inhibit the polarization state random fluctuation in the optical path and solves the problem of polarization-induced fading of a conventional hydrophone. The invention adopts the quasi-reciprocity optical path scheme, so that the immunocompetence for the environmental interference is strong. The invention also adopts the reflective optical path, a signal passes through the acoustic probe back and forth for twice and the efficiency of detecting a sound pressure signal is twice of that of a conventional optical fiber sensor and the sensitivity is effectively improved; and the optical fiber is used as an information sensing and transmitting medium, so that the optical fiber hydrophone cannot be interfered by the electromagnet.

Description

technical field [0001] The invention belongs to the technical field of optical fiber sensing, and in particular relates to an optical fiber hydrophone adopting a reflective quasi-reciprocal optical path for detecting sound pressure by using interference light phase. Background technique [0002] Sound waves are currently the most effective carrier capable of transmitting information over long distances in the ocean. Detecting the space-time structure of the sound field formed by the sound wave carrying the signal in the ocean is an important means for underwater detection, identification, communication and environmental monitoring. It can be used for long-distance military target detection, seabed mineral development, fish schools Detection can also be used for telemetry of ocean dynamic processes (internal waves, circulation) and detection of ocean and land seismic waves. Therefore, advanced underwater acoustic detection technology is of great significance to national econ...

AI Technical Summary

Problems solved by technology

However, there are inherent problems in these two interferometers. For example, it is difficult to ensure that the lengths of the two interference arms are the same. In some applications, the optical path difference between the two arms will be artificially increased. Convert phase noise to intensity noise

In addition, the optical paths of the two coherent beams are different, and the polarization states of the two beams will fluctuate randomly, which is difficult to keep consistent, which will lead to a decrease in the contrast of the interference signal, or even zero contrast in severe cases

Although the fiber optic hydrophone based on the Sagnac interferometer solves the problem of random fluctuations in the polarization state, because the Sagnac interferometer is a reciprocal optical path system, it has inherent insensitivity to low-frequency signals and has certain limitations.

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