Research On Key Technologies Of All-fiber Ocean Temperature And Depth Sensor

The all-fiber ocean temperature and depth sensor has the advantages of anti-electromagnetic interference,intrinsic insulation,small volume,low cost,easy multiplexing,high sensitivity,and easy signal transmission over long distances.It is a useful supplement to the traditional electric ocean temperature and depth sensor and can be used for the low cost temperature and depth sensing chain.At the same time,the all-fiber ocean temperature and depth sensor is easy to integrate into the fiber optic hydrophone detection system,and the in-situ real-time monitoring of the marine power environmental elements can be realized synchronously,which helps to improve the detection performance of the fiber optic hydrophone detection system.Based on extensive research on domestic and foreign research,this paper studies the key technologies for all-fiber ocean temperature and depth sensor based on polarization-maintaining fiber Bragg grating sensing technology and extrinsic fiber Fabry-Perot interferometer sensing technology.The main research work and innovations of the thesis are as follows:(1)The research on the structural design of all-fiber ocean temperature and depth sensor is conducted.The structure of a polarization-maintaining fiber Bragg grating packaged with a mixture of aluminum sleeve and epoxy resin,and the extrinsic fiber Fabry-Perot interferometer formed by a fiber-optic pigtail end face and stainless steel sheet at the bottom of the aluminum casing is proposed.The polarization-maintaining fiber Bragg grating and the extrinsic fiber Fabry-Perot interferometer are cascaded into the all-fiber ocean temperature and depth sensor.(2)The research on high-precision detection technology of multi-parameter simultaneous sensing signals is carried out,and the method of signal detection and analysis based on wavelet transform algorithm,Gaussian fitting peak finding algorithm and cross-correlation detection algorithm is proposed.(3)The experimental research on the fabrication technology and sensing characteristics of the all-fiber ocean temperature and depth sensor was carried out.The experiments were completed by simulating the marine environment.The experimental results show that the temperature sensitivity of the fiber-optic ocean temperature and depth sensor can reach 25.52pm/?(left peak)and 24.45pm/?(right peak)respectively.The pressure detection sensitivity can reach 35.78 ?m /MPa,and the pressure detection range is about 0-4 MPa.The cross sensitivity of the sensor is measured at the same time.The experimental results show that the pressure sensitivity of the temperature sensor is1.33pm/MPa(left peak),1.33pm/MPa(right peak),and the temperature sensitivity of the pressure sensor is about 0.2 ?m /?.The feasibility of this design scheme to solve the cross-sensitivity problem of the sensor is analyzed.