Spectral Characteristics Of Low Frequency Underwater Acoustic Signal Based On Optical Micro-ring Resonator

With the improvement of marine strategic status,how to protect and develop marine resources has become an extremely important topic.Because of the advantages of easy integration,low insertion loss,low crosstalk and no need of end feedback,the micro ring resonator provides the direction for the accurate measurement of the ocean low frequency underwater acoustic signal.The purpose of the paper is to provide the theoretical support for the development of higher sensitivity and wider dynamic range underwater acoustic measurement equipment.The paper focuses on the analysis of the parameters of micro ring resonator and the improvement of the sensor performance,the main tasks are as follows:First,the paper reviews the research progress of hydrophone technology at home and abroad,and reviews the basic theory and technology of marine acoustic environment.Vector hydrophone is a hot research direction in the field of underwater acoustic signal measurement.The paper analyzes the directivity and sensitivity of two channel parameters of vector hydrophone,deduces the mathematical relationship between the aM and pM,vM and M?.It has proved the application of vector hydrophone in low frequency underwater acoustic signal measurement advantage.Then,the paper has studied the structure of various micro ring resonators.The transfer function of micro ring resonator is obtained with transfer matrix method.Combined with the effective index method,coupled mode theory and the finite difference time domain method FDTD(Finite Difference Time Domain,FDTD),the relationship between the derived resonant radius,effective refractive index and the transfer function,the output spectrum obtained by simulation.In order to improve the performance of the sensor and the parameter of the resonant structure,the output spectrum of the series symmetric three micro ring resonator and parallel symmetric micro ring resonator has been studied.The results show that this method can effectively improve the sensor performance.Finally,in order to measure the low frequency underwater acoustic signal,a cantilever beam supporting structure is designed.At the same time,the performance of the structure is analyzed.With a single micro ring resonator as a low frequency acoustic signal acquisition device,the paper has designed a low frequency acoustic signal acquisition device.Based on this method,the linear relationship between the resonant wavelength shift and the underwater acoustic pressure is obtained.The simulation results show that the structure has higher sensitivity and wider dynamic range.And the performance of the dual ring resonator is analyzed as the sensing structure.The output spectrum shows that the better performance can be achieved by using the micro ring resonator array.