Optical fiber sensor used for simultaneously measuring temperature, salinity and depth of sea water, and preparation method thereof

Abstract

The invention provides an optical fiber sensor used for simultaneously measuring the temperature, salinity and depth of sea water, and a preparation method thereof. A groove is made on the side deviating a fiber core through femtosecond laser etching and chemical corrosion; a segment of arc-shaped waveguide is written into cladding on the other side deviating the fiber core by utilizing the characteristics of femtosecond laser changing optical fiber refractive indexes through a rotary processing platform; the two ends of the waveguide are connected to the fiber core; and a double Mach-Zehnderinterferometer (MZI) cascade structure is made. A sensing structure can form the sensor after encapsulation. The transmission spectrum of the double MZI cascade sensor has three characteristic wavelengths with different contrast in a wavelength range of 1,300-1,600 nm, and the three characteristic wavelengths have different response sensitivity on the temperature, salinity and depth of sea water,so that the corresponding temperature, salinity and depth information of the sea water can be obtained through the change values of the characteristic wavelengths and the combination of sensitivity matrixes. The provided sensing element is compact in structure and high in mechanical strength and measuring sensitivity, and is an effective means of realizing the accurate measuring of multiple parameters of the sea water.

Description

technical field [0001] The invention belongs to the field of optical fiber multi-parameter measurement, and provides an optical fiber sensor for simultaneous measurement of three parameters of seawater temperature, salt and depth and a preparation method. Background technique [0002] The measurement of seawater parameters plays an important role in the development of marine resources, environmental protection and climate monitoring, among which the most typical parameters are the temperature, salinity and depth of seawater. The application of electrical sensors in the marine environment is easily affected by power supply, seawater corrosion and electromagnetic interference, while optical fiber sensors have anti-electromagnetic interference, corrosion resistance, small size, light weight, compact structure, high sensitivity, and can realize long-distance distributed measurement, etc. Advantages, it has great advantages in the field of seawater parameter measurement. [0003...

AI Technical Summary

Problems solved by technology

However, due to the influence of ambient temperature changes in the actual measurement process, errors will be introduced into the measurement results, resulting in inaccurate measurements

China Jiliang University proposed an in-line Mach-Zehnder interferometer based on femtosecond laser-written linear waveguide (application number: 201810487679.X), which can be used for high temperature and bending measurements, but the interferometer is located inside the fiber and has not been integrated with It is difficult to measure the salinity of seawater when exposed to external solutions

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