Research On The Influence Of Packaging Material For The Sensitivity Enhancement Of Fiber Laser Sensor

Fiber laser sensors find extensive application in medical,communication,optical sensing and scientific researching areas because of its small size,high efficiency and immunity to electromagnetic.However,the application of optical fiber is limited for its slender and fragile,vulnerable to external damage.A solution is to encapsulate specific materials that act as sensitizers and protectors around it.This paper mainly studies the packaging material on the distributed Bragg reflector(DBR)fiber laser sensor's sensitivity.The influence of package materials on fiber laser is analyzed by COMSOL software simulation analysis and experiment.This paper firstly introduces the research background and working principle of DBR fiber sensor,as well as its writing method,and focuses on the principle of it on the detection of ultrasound,low frequency sound wave,pressure and magnetic field.Secondly,this paper introduces the present packaging technology and materials.The epoxy resin was selected as the experimental material.We established an acoustic-solid coupling model using COMSOL software to simulate underwater acoustic signal sensing.The sensitivity gain was about 30 dB compare to bare fiber when using thin encapsulation structure in numerical simulation.Then,we use the thin film structure of epoxy resin encapsulation DBR fiber sensor to measure the underwater ultrasonic and the low frequency sound wave.The results show that the polymer material can effectively improve the sensitivity of the DBR fiber optic sensor,but the different package structure is different when measuring different parameters.Cylindrical package structure optical fiber sensor is more suitable for the measurement of underwater acoustic signal,the chip package structure is more suitable for the measurement of low frequency vibration.In addition,the DBR fiber laser is placed in the magnetic fluid of the epoxy resin.We measured magnetic field using magnetic properties of magnetically controlled refractive index.The results show that the beat frequency of DBR fiber laser is gradually decreased with the increase of the current.The magnetic field sensitivity is about 0.103MHz/Gs.