Research On Fiber Optic Multi-parameter Sensor Of Temperature Salinity And Depth

Temperature,salinity,and depth are the most basic measurement parameters in ocean observations.In the development and protection of marine resources,accurate measurement of the basic parameters of temperature,salinity and depth is of great significance.Traditionally,detection of seawater temperature,salinity and depth mostly uses Conductivity-temperature-depth(CTD)profiler,but there are certain limitations in miniaturization,synchronous measurement and distributed detection.In recent years,the rapid development of optical fiber sensors has been widely used in multi-parameter measurement due to its compact structure,anti-electromagnetic interference and easy networking.In this paper,combined with the demand for measurement of temperature,salinity and depth,using the combination of multiple sensing units,a variety of reflective multi-parameter sensing probes are designed to achieve measurement of seawater temperature,salinity and depth.The main research work includes the following aspects:First,the types and characteristics of ocean temperature,salinity and depth sensors at home and abroad are analyzed.The structure of fiber optic multi-parameter detection is summarized and compared,and the basic principle of sensor probe design based on the combination of multiple sensing structures is determined.The theories and sensing principles related to sensors are studied to provide a certain theoretical guarantee for experiments and simulation analysis.Then use Rsoft software to optimize and analyze the three parameters of cone structure,cone waist diameter and cone waist length,and it is obtained that under the cone-cylinder structure,when the cone waist diameter is 7.2um and the cone length is 1100um,the refractive index sensitivity is higher.Introduce the simulation method of COMSOL software under different temperature salinity and depth.A simulation model was built to verify the feasibility of multi-sensing unit combined measurement and provide theoretical support for the preparation of sensors.Finally,a micro-cone temperature,salinity and depth sensor was designed and manufactured.A complete temperature,salinity and depth detection system was built,and the performance of the sensor was optimized.The fabrication of the micro-cone and thin-film Fabry-Perot cavity were introduced in detail and then assembled to form a sensor probe,which proved that the structure can realize the measurement of seawater temperature,salinity and depth.The sensitivity is:0.083 1nm/?,-99.94nm/RIU and-0.233nm/cm.The manufacture and measurement of stable mismatch sensor probe was introduced in detail.Firstly,introduce the manufacturing method of the mismatch structure and optimize it according to the transmission spectrum.The spectrum corresponding to each feature is extracted by Fourier transform,and the sensitivity of the sensor probe of this structure to temperature,salinity and depth is 0.0505nm/?,-79.83nm/RIU and-0.189nm/cm,respectively.The structure for the sensor probe package is designed,and it may be used in high-pressure experimental tests.This article mainly completes the design of the new structure of the optical fiber-based temperature salinity and depth sensing probe,simulation analysis,sensing principle analysis,sensor packaging design and determination of the multi-parameter demodulation scheme.In order to solve the problems of miniaturization of temperature,salinity and depth sensors,measurement of multiple parameters,and to improve the detection performance of the sensor,some implementation scheme is provided.