Research And Application On Optical Fiber Fabry-Pérot Sensor

Optical fiber Fabry-Pérot sensor have broad prospects in practical applications.This paper mainly studies and discusses their applications.The details are shown as following:1.Referring to a large number of references,to introduce the development background,fabrication principle and development prospect of optical fiber microfluidic velocity sensor and optical fiber curvature sensor.2.A fiber microfluidic velocity sensor based on a bare fiber adapter?BFA?was proposed and demonstrated.Ceramic end face in BFA was covered by polyethylene?PE?film,in which the inserted SMF can be moved freely.The end face of the SMF and the PE film composed a Fabry-Pérot?F-P?construction.Due to PE film sustaining different press with different microfluidic velocity,the F-P cavity length was changed.The velocity can be measured by monitoring the transmission spectrum.In our experiment,three cavity lengths were measured.The experimental results showed that the achieved maximum sensitivity to microfluidic velocity is 0.048dB/??m/min?and0.0059nm/??m/min?.Also,responses of PE film thickness and microfluidic concentration to the proposed sensor have been measured in the experiment.The sensor can be used for low velocity and high sensitivity microfluidic velocity detection,especially in micro-channels such as biological blood vessels.3.A capillary-based fiber microfluidic velocity measurement system was proposed and demonstrated.The principle of the sensor was analyzed and the manufacturing process of the sensor was introduced in detail,and it was used to measure the microfluidic velocity.The sensor is composed of SMF,capillary glass tube and poly tetra fluoroethylene?PTFE?tube.In this experiment,three kinds of fiber-optic F-P sensors with different cavity lengths were fabricated,and the influence of the length of the fiber F-P cavity on the microfluidic velocity was studied.By monitoring the output interference spectra of three lengths of cavity length?20,30,50?m?,three microfluidic velocity sensitivities of 0.0034 nm/??m/min?,0.0037 nm/??m/min?,and 0.0049nm/??m/min?were obtained,respectively.The microfluidic velocity sensor can directly measure the velocity of the microfluidic,and has the characteristics of non-contact,high sensitivity and low cost.4.A fiber sphere embedded long-period fiber grating?LPFG?sensor has been proposed and fabricated for curvature measurement with high sensitivity.Compared with the normal LPFG,the embedded fiber sphere divides LPFG into two cascaded F-P structures and two new dips of the output spectrum have been observed.The curvature measurement can be realized by monitoring the shift of the two dips.Experimental results show that the highest curvature sensitivity is up to-104.642 nm/m^-11 with the curvature ranging from 0 to 0.71m^-1.The temperature response of the sensor has also been studied and quadratic linear relationship between the dip shift and the temperature has been observe d.The highest temperature sensitivity is 0.36 nm/?with the temperature range between 20?to 90?.