Sagnac Optical Fiber Hydrophone Sensitization Technology Research

As the doped fiber manufacturing technology, the ptical photolithography technology and the optical fiber laser in recent years, Optical fiber laser hydrophone are a new kind of high precision fiber optic acoustic sensor. Optical fiber laser hydrophone adopted line Line cavity fiber laser as an acoustic cavity fiber laser, and demodule sensitive elements of the signal of underwater acoustic by non-equilibrium interferometer with a high sensitivity, the advantage of simply structure, smaller volume, being especially suitable for used to construct the large-scale superfine light fiber hydrophone array. In this paper, we discussed deeply theoretical of and make a simulation of the Sagnac fiber-optic hydrophone sensitivity problem.In this article we firstly analyzes the Sagnac optical fiber hydrophone’s response characteristics of acoustic signal and its main influencing factors, and combing with Marine shallow-water acoustic field propagation characteristics, analysis the measurement parameter relations in far field properties of point source with far-field characteristics, The results show that the Sagnac sound pressure phase sensitivity of fiber-optic hydrophone is a cyclical change, its of changes’ s cycles with time delay in system is proportional to the length of fiber.The high and low of sensitivity is proportional to the length of the sensing optical fiber probe,the sound field of shallow sea environment, the size of the the optical fiber hydrophone’s sensitivity is only related to the frequency of the sound source, if we combine theprecision requirements of actual using. The result also show that considering complexity of ocean acoustic field, when set practical the sagnac optical fiber hydrophone, we should as far as possible to increase the length of the sensing optical fiber, select correctly the fiber length of delay time according to need. At the same time, we have to reduce the system noise, we should use low coherent light source, reduce polarization’s influence decline, etc.Improve the response of the fiber Bragg grating sensor sensitivity is better way that improveing the detection precision of the fiber bragg grating sensing system, Using polymer encapsulation is a simple and effective way of fiber Bragg grating pressure protection and sensitization. the pressure sensing characteristics of fiber grating hydrophone probe using the spindle assembly construction were studied, by the finite-element software ANSYS, we compare and analysis the polymer sensing effectsthe of different material properties, the results show that the spindle structure’spressure sensitivity having certain properties materials is about 200 times higher than the bare fiber, hasing a good practical value.In this paper, analysising of the sagnac optical fiber hydrophone’s sensitivity has a lot promote for the sagnac fiber optic hydrophone in practical, Sagnac optical fiber hydrophone will get extensive application for its unique properties in the future development.