Research On Mode Feature And Sensing Characteristics Of Fluid Controling System Based On Side-polished Fiber

Microstructured optical fibers(MOF)have a unique cladding structure that enables the interaction of light and matter through the integration of materials.However,the disadvantage of traditional material integration technology is that it is impossible to mix and replace filling materials in the process of real-time optical signal monitoring.The emergence of fiber-optic fluid control technology has broken this limitation and realized the detection of refractive index,concentration and other characteristics of fluid materials in the process of optical signal monitoring.Therefore,it is of great academic significance to study the fluid control technology with stable structure,flexible design and high integration.Based on the analysis of the theoretical model of the fluid system,this paper designs and implements a kind of fluid control system based on side-cast optical fiber.In the theoretical part,the mode characteristic analysis based on the birefringence characteristic and resonance characteristic is carried out to clarify the action process between the modes and lay the theoretical foundation for the system construction.Then,by preparing side-cast optical fiber and solving the problem of welding alignment and parameters,the fluid sensing system with fast filling and high integration degree is realized.Finally,the fluid system is integrated with materials and its sensing characteristics are studied.The main research contents are as follows:1.Three kinds of typical grinding shapes and corresponding theoretical models of the fluid control system are proposed through the design of the throwing grinding scheme of the contralateral throwing fiber.Mode feature analysis based on birefringence was carried out for models with different shapes and depths of grinding.Two schemes capable of producing high birefringence were used to realize the refractive index sensing of Sagnac interferometer,and the refractive index sensitivity of 3659.54 nm /RIU and 3123.76 nm /RIU were obtained,respectively.Then,two kinds of polishing schemes with different depths were designed to realize the resonance coupling between the fiber core and cladding layer,and the sensing characteristics of the refractive index and temperature of the strongest resonance point were studied,and the tuning sensitivity of-6338 nm /RIU and 2.5nm /? was obtained.2.The problems of poor surface quality and low light power loss are solved by using the wheel mechanical grinding method and the production processes of coarse grinding,fine grinding,fine polishing and fire polishing.In order to build a five-layer air hole fluid channel on one Side and design the polishing parameters,a Side Polished Fiber(SPF)with a length of up to 2 cm and a depth of up to 57 ?m was prepared.It also solves two technical difficulties in the alignment of optical fiber end face and the optimization of welding parameters,and successfully fusing the side-cast optical fiber and the microstructure optical fiber,thus realizing the establishment of the fluid channel.3.The use of auxiliary pressure device two liquids with high refractive index win min from lateral opening into the fluid channel produced photonic band gap effect,and by using high precision temperature control box to adjust and control the refractive index of the internal fluid material,to study the fluid flow control system proposed in this paper in smaller refractive index range of refractive index sensing properties,received good response as a result,the linearity and refractive index sensitivity were as high as 6457.76 nm/RIU and 6025.85nm/RIU.