Research On Design And Sensing Properties Of Silica Micro/nanofiber Resonator Ring Sensing Probe

Being a noval sensor device,and using light as the transmission medium,optical fiber sensors have the unique advantages of anti-electromagnetic interference,corrosion resistance,small size,high integration and high sensitivity.The micro/nano fiber can highly sense the external environment reling on its strong external evanescent field.Compared with ordinary optical fiber sensors,the micro/nano fibers sensors have some prominent sensing performances in sensitivity,resolution,response time,etc.In recent years,the micro/nano fibers sensors have been widely concerned by scholars both at home and abroad,and have became one of the main branches and forefront direction of advanced optical fiber sensing technology.Based on the mechanical,thermal and optical basic properties of silica micro-nanofiber,a silicon micro/nano fiber resonator ring sensing probe was designed,and its temperature and strain sensing characteristics were studied.The extremely small size of the silica micro/nano fiber resonant ring results in that it is not easy to preserve.Therefore,my subject mainly aims at realizing independent and practical sensing probes and improving the sensing performance.My subject chose PDMS(polydimethylsiloxane)to encapsulate the sensing probe.PDMS has the excellent environmental adaptability and is used to improve the practicability and lifetime of the sensing probe.At the same time,PDMS has a smaller Young's modulus,a higher thermal-optical coefficient,thermal-expansion coefficient,and Poisson's ratio compared with silica,which effectively increases the sensitivity of the temperature sensing and the strain sensing of the sensing probe,and has a great potential practical value.The main contents are listed as follows:(1)The enhancement principle of silica micro/nano fiber based on evanescent field was simulated and analyzed by Comsol,the optical properties of silica micro/nano fiber resonant ring and the feasibility of its application in the sensing field are explored.In addition,the different preparation methods of silica micro/nanofiber and silica micro/nano fiber resonant ring were analyzed and compared.Finally,the application of the silica micro-nano fiber ring in temperature and strain measurement is proposed.(2)The advantages and disadvantages of several typical silica micro/nano fiber resonators are summarized and analyzed.The temperature and strain sensing probe based on a knot micro/nano fiber resonant ring was identified.The advantages of evanescent coupling method was analyzed.The output spectrum and performance indicators of silicon micro/nano fiber resonant ring were analyzed and the output spectra were simulated by Matlab.(3)Selecting the appropriate material PDMS to package silicon micro/nano fiber resonant ring can increase the sensitivity and stability of the microring sensor.The packaged structure of sensing probe was designed and the sensing mechanism of the silicon micro/nano fiber resonator were analyzed.Its output spectrum as a function of the refractive index change or the expansion effect were simulated.Finally,the relationship between the temperature sensing and strain sensing of PDMS package silicon micro/nano fiber resonant ring was theoretically derivated.(4)Based on the flame-stretching method and the mechanical stretching method,the micro/nanofiber with a relatively uniform mass was fabricated.I improved the MKR manufacturing method and prepared MKR with lower loss.Finally,the independent sensor probe packaged by PDMS was fabracated.(5)The temperature and strain sensing system based on PDMS packaged are built in the laboratory conditions.In the temperature sensing experiment,the diameter of micro/nano fiber is 8.52?m and the diameter of MKR is 4.38mm.The size of the packaged sensing probe is 7.6cm in length,2.6cm in width and 2mm in thickness.The temperature sensing sensitivity is 1.79nm/? and the resolution is 0.011? in the temperature range of 30-40?.The temperature sensing characteristics of MKR with different micro/nano diameters and different ring lengths were analyzed.Then,the transverse load sensing characteristics were studied again.When the diameter of micro/nano fiber is 8.52?m and the diameter of MKR is 4.38mm,a transverse load sensitivity of 91pm/N was obtained in the range of 10N-51N.The corresponding strain sensitivity was 0.039pm/??.And the transverse load sensing characteristics of MKR with different micro/nano diameters and different ring lengths were analyzed.