Research On The Preparation And Sensing Characteristics Of Optical Fiber Sensors Based On Fiber Substrate

In recent years,more and more researchers pay attention to the optical fiber sensor technology,and more and more optical fiber sensors are designed and applied to the engineering field.Among them,all fiber sensor has become the focus of research because of its advantages of simple structure,easy preparation and low cost.At present,most of the all fiber sensors are based on the common cylindrical optical fiber.Different from the ordinary cylindrical fiber,the special-shaped fiber substrate has the characteristics of non-circular symmetry.It is easy to modulate the core structure of the optical fiber by two times processing on the non circular symmetrical abnormal optical fiber substrate.The optical fiber sensors formed by modulating the fiber core often have good sensing characteristics.In order to explore the modulation effect of different special-shaped optical fiber substrates and different secondary processing methods on the core structure,as well as the change of sensing characteristics,in this paper,a variety of new optical fiber sensors were fabricated based on special optical fiber substrate,and the sensing characteristics were studied.Firstly,two thin films with a certain distance were made on a common single-mode fiber to form a double sheet structure.And an elliptical core MZI was prepared based on this structure.Secondly,three kinds of new LPFG were fabricated on the thin fiber substrate,which were thin-film CO₂-LPFG,CO₂-LPFG fusion cone type and elliptical core type LPFG.And their corresponding sensing characteristics were studied.Among them,the cores of cone-shaped LPFG and elliptical core type LPFG were modulated into ellipses.The elliptical core LPFG had the characteristics of low temperature sensitivity and high strain sensitivity.At last,a new type of arch core LPFG was fabricated on D-type fiber substrate by fixed-point discharge,and its temperature,torsion and bending sensing characteristics were studied.The experimental results show that the core of the arch core LPFG was modulated into an arch,and the arc of the arch core was controllable.The arch core LPFG can distinguish bending in different directions and had good sensitivity.Based on the special-shaped optical fiber substrate,the optical fiber sensors with good sensing characteristics,such as elliptical core LPFG and arched core LPFG,were fabricated by arc discharge,electrothermal melting taper and fixed-point heating.The effects of different substrate and different secondary processing methods on the structure and sensing characteristics of optical fiber were studied.