Research On Optical Fiber Sensing Detection Technology Based On VCSEL

VCSEL(Vertical Cavity Surface Emitting Laser)is a crucial new light source for short distance transmission in the field of optical fiber communication at present.The research of VCSEL laser is getting mature with the development of nano laser technology.And it’s increasingly being used in sensors.Fiber optic sensors are widely used in harsh and complex environment engineering because of their unique advantages such as small size,long transmission distance,high measurement accuracy,strong electromagnetic resistance,high temperature resistance and corrosion resistance.Therefore,it is of great significance to study the detection direction of VCSEL laser in optical fiber sensing.Based on VCSEL laser,low power fiber grating interrogation system and laser methane sensor system are designed in this thesis.The main work contents involved are as follows:By analyzing the spectral characteristics of VCSEL laser,a low power fiber grating interrogation system is designed.The basic ideas and main components of the interrogation system are introduced in detail.The basic idea is to use the wavelength of methane absorption peak as the reference wavelength to measure and calculate the wavelength change of fiber Bragg grating and calculate the corresponding physical quantity parameters according to the corresponding relationship between the physical quantity to be measured and the wavelength.The main components of the system include current drive module,photoelectric conversion module,data acquisition module and upper computer module,and the related hardware circuit design is described.The experimental results show that the interrogation accuracy of the system is 3pm,the effective interrogation range is 3.5nm,and the power consumption is less than 100 m W in the measuring range of 10～40℃.Based on Tunable Diode Laser Absorption Spectrometry technology and direct absorption spectroscopy,a methane sensor detection system for VCSEL laser is designed.The whole composition of the detection system is studied,including signal generation module,gas absorption module and signal receiving module.To simplify the system structure and save the cost,an optical path extension scheme is proposed to improve the performance of the optimized system.The feasibility and reliability of the scheme are verified by some experiments.