Research On Spatial Resolution Optimization Technology Of Optical Frequency Domain Reflectometer

Optical frequency domain reflectometry(OFDR)technology is one of the distributed optical fiber sensing technologies.OFDR technology uses optical fiber as a signal sensing and transmission medium.It uses the dielectric and non-conductivity of optical fiber,antielectromagnetic interference,small size,high sensitivity,and can work in various extreme positions.By measuring the Rayleigh scattering signal returned along the optical fiber,the measurement or monitoring of stress,strain,temperature,vibration,3D shape,flow rate,magnetic field radiation and gas along the optical fiber transmission path can be realized.Nowadays,sensors are gradually becoming more intelligent and networked.Compared with the same type of optical time domain reflection(OTDR)based on Rayleigh scattering,OFDR sensors have the characteristics of high resolution,large dynamic range and good temperature performance in a short distance,so they are very useful in a large number of sensing scenarios,such as measuring temperature,strain,vibration,pressure,magnetic field,refractive index,radiation,three-dimensional shape,gas,gas flow rate and so on.In the application of OFDR technology,the spatial resolution and transmission distance of OFDR system are affected due to the nonlinear effect of light source and polarization fading technology,which will limit the performance of optical fiber sensing system to a certain extent.In this paper,the principle and performance of optical frequency domain reflection technology are analyzed,and the spatial resolution of the system is optimized.Based on the OFDR high spatial resolution and high performance sensing technology,a new esophageal manometry sensor is proposed and verified by experiments.The specific arrangements of this paper mainly include the following aspects:(1)The research background of optical fiber sensing technology is introduced.The research status of distributed optical fiber sensing technology OTDR and OFDR based on Rayleigh scattering is analyzed.The current development trend and performance characteristics of OFDR technology are introduced.(2)The OFDR technology is analyzed theoretically,including Rayleigh scattering principle,heterodyne detection principle and optical frequency domain reflection signal transmission and sensing principle.(3)Analyze the parameter influence and performance constraints of OFDR technology.Aiming at the nonlinear effect and polarization fading effect,a compensation method is proposed and a system verification is built.(4)By designing the sensor structure,the finite element simulation analysis method is used to optimize the experiment.By processing the designed structure,the OFDR system is used for experimental verification and testing.Finally,the strain value of 39.67 μεis realized at the sensing distance of 10 mm.