Research On Sensing Characteristics Of Single-cavity And Dual-cavity Hybrid Fiber-optic Fabry-Perot Interferometer

Fiber-optic sensor has many advantages,such as compact structure,strong electromagnetic interference resistance and high sensitivity,etc.It is widely used in many sensing fields,such as temperature,strain,pressure,refractive index sensing and so on.Among the many fiber-optic sensors,the fiber-optic Fabry-Perot interferometer sensor has its unique advantages,such as realization of temperature insensitivity as well as high-temperature sensitivity,simultaneous measurement of dual-parameter,excellent stability and so on.So the fiber-optic Fabry-Perot interferometer sensor has developed very rapidly.This thesis is based on research of the sensing characteristics research of fiber-optic Fabry-Perot interferometer.The main research contents are listed as follows:Firstly,we reviewed the research progress of fiber-optic interferometer sensor,and analyzed the research status of fiber-optic Fabry-Perot interferometer sensor.Through the analysis on the research status of fiber-optic Fabry-Perot interferometer sensor,some shortcomings of the current fiber-optic Fabry-Perot interferometer sensor are found.Secondly,currently reported dual-cavity hybrid structured fiber-optic Fabry-Perot interferometer needs special treatment to achieve transverse load sensitive and temperature insensitive.In order to be convenience for application,a large size air bubble cavity fiber-optic Fabry-Perot interferometer is made by fusion splicing in this paper.This air bubble cavity fiber-optic Fabry-Perot interferometer can achieve transverse load sensitive and temperature insensitive,and also be applied to strain sensing.It does not need special treatment in sensing application,so it is very convenient to apply.In addition,the closed-cavity fiber-optic Fabry-Perot interferometer applied to strain sensing has been widely reported,and the open-cavity fiber-optic Fabry-Perot interferometer applied to strain sensing is rarely studied.This paper studies the strain sensing characteristics of open-cavity fiber-optic Fabry-Perot interferometer.The strain sensitivity of the open-cavity fiber-optic Fabry-Perot interferometer made by large lateral offset splicing is higher than the common closed-cavity fiber-optic Fabry-Perot interferometers reported.At the same time,the open-cavity fiber-optic Fabry-Perot interferometer can also be used in refractive index sensing.In order to avoid the impact of the external environment,the open-cavity fiber-optic Fabry-Perot interferometer can be packaged into SiO2 microtubule in strain sensing application,and this packing method has little effect on strain sensitivity.Furthermore,various dual-cavity hybrid structured fiber-optic Fabry-Perot interferometers have been applied to many fields of simultaneous measurement of dual-parameter,such as temperature and pressure,temperature and refractive index,temperature and strain.However,simultaneous measurement of transverse load and temperature is not reported for dual-cavity hybrid structured fiber-optic Fabry-Perot interferometers.This paper presents and makes a new type of dual-cavity hybrid structured of air bubble and SiO2 cavity fiber-optic Fabry-Perot interferometer,and it can realize simultaneous measurement of transverse load and temperature.At present,dual-cavity hybrid structured fiber-optic Fabry-Perot interferometer in the simultaneous measurement of transverse load and temperature has not been reported.Finally,it is only 5.18 pm??? for the sensitivity of the reported dual-cavity hybrid structured fiber-optic Fabry-Perot interferometer used in the simultaneous measurement of strain and temperature,and the strain sensitivity is very low.This paper presents a new type of dual-cavity hybrid structured of open-cavity and SiO2 cavity fiber-optic Fabry-Perot interferometer,and it can realize simultaneous measurement of strain and temperature.The strain sensitivity is 28.95 pm??? for this dual-cavity hybrid structured of open-cavity and SiO2 cavity fiber-optic Fabry-Perot interferometer,it is over 5 times more sensitive to strain than the reported dual-cavity hybrid structured fiber-optic Fabry-Perot interferometer.The research in this paper overcomes some shortcomings of the current fiber-optic Fabry-Perot interferometer sensor,and improves the performance of the fiber-optic Fabry-Perot interferometer sensor,and makes the fiber-optic Fabry-Perot interferometer sensor more practical and more promising.