Research On Influence And Suppression Methods Of Noise And Temperature Of Dual-Polarization Optical Fiber Interferometer

Interferometric fiber optic sensors are widely used in measurement of many physical quantities due to the unique advantages such as high measurement accuracy,large dynamic range,and the ability to be used in complex environments.However,measuring noise and temperature effect limit the resolution and stability of interferometric fiber optic sensors.The core of the interferometric fiber optic sensor is the fiber optic interferometer,so it is the most fundamental and primary task to improve the performance of the interferometer.In the past,significant efforts have focused on measuring noise and temperature effect of the fiber optic interferometer,which are driving the evolution of fiber optic sensing technology.This thesis has carried out a series of studies on the two goals of “reducing measuring noise” and “suppressing temperature effect” to improve the performance of the fiber optic interferometer.The main research contents are as follows:Firstly,we studied the main factors affecting the noise of the interferometer,including laser source noise,optical path noise,and demodulation system noise.The mechanism of each noise was analyzed in this thesis,and we obtained the influence of noise factors on the noise floor through experiments.The combination of parameters that minimizes noise can be set according to actual needs.Based on this research,a low-noise short-arm length Mach-Zehnder interferometer was designed in this thesis.Secondly,temperature effect is a common problem in fiber optic interferometers,and eliminating temperature effect is critical to interferometers.In this thesis,the process of temperature influence on the fiber interferometer was analyzed.We designed a dual-polarization full polarization-maintaining fiber interferometer by establishing a theoretical model.The experimental results show that this interferometer can eliminate the temperature effect,suppress the phase shift affected by temperature,and reduce the low frequency noise.Thirdly,this thesis proposed a high-performance fiber optic sensor for simultaneous measurement of displacement and temperature based on the research results of noise suppression and temperature effect elimination.By constructing a theoretical model,this sensor suppressed temperature effect and achieved simultaneous measurement of displacement and temperature.In this thesis,a series of performance tests were performed on the sensor.The work in this thesis has obtained the method of reducing the measuring noise of the interferometer and the method of suppressing the temperature effect,which provides a powerful basis for the development of high stability and high-resolution fiber optic sensors.