Study On Spectral Characteristics Of Sagnac Ring Embedded With Partial Cladding Fiber

Fiber Sagnac ring has the advantages of high stability,low cost,simple structure and flexible design,and has been widely used in fiber communication and sensing fields.Combining Sagnac ring with existing fiber structures will bring new spectral characteristics that can be used to develop communication and sensing applications.In this paper,the embedded Sagnac ring of partially coated fiber are taken as the research object.Based on the strong evanescent field characteristics of partially coated fiber,the spectral characteristics of the embedded Sagnac ring of partially coated fiber are studied by combining theoretical analysis and experimental research.The main work of this paper is as follows:1.The development of fiber Sagnac ring sensing structure at home and abroad,the research on the characteristics of micro-nano fiber Bragg grating(MFBG)liquid refractive index sensing and the research status of graphene membrane fiber structure sensing are reviewed.2.Experimental study on the refractive index sensing characteristics of Sagnac ring embedded with FBG cladding.Firstly,the model field distribution of partially coated FBG structures with different diameters is simulated,and then the refractive index experiment is carried out on the Sagnac ring sensor structure with partially coated FBG embedded.The experimental results show that the sensitivity of FBG embedded structure with partial cladding is 6.683nm/RIU in the low index range and 29.624nm/RIU in the high index range.3.Experimental study on refractive index sensing characteristics of Sagnac ring with FBG embedded in partially coated graphene membrane under optical power control.Experimental study on optical power control characteristics of Sagnac ring coated with graphene films of different thickness and partially coated with FBG embedded in Sagnac ring is conducted,experimental results show that the sensitivity of the Bragg grating embedded Sagnac ring optical power control can reach 94.61pm/mw when coated with graphene for three times.On the basis of coating the surface of partially coated FBG embedded Sagnac ring with graphene for three times,the experimental study on optical power control characteristics of grating embedded Sagnac ring with different fiber arm length differences is continued,experimental results show that the sensitivity of the raster-embedded Sagnac ring can reach 162.24pm/mw when ?L=3cm.4.Experimental study on the refractive index sensing characteristics of Sagnac ring with partial cladding single-mode fiber cascade FBG embedded fiber.The refractive index characteristics of fiber cascade FBG embedded Sagnac ring with partial cladding length of 2cm,4cm and 6cm of single-mode fiber are studied,and the sensitivity of interference wavelength with refractive index solution is found to be 2815.619nm/RIU,1996.33nm/RIU and 1216.027nm/RIU,respectively.The experimental results show that the shorter the length of the single-mode fiber to part of the cladding,the higher the energy exchange between the fiber and the outside world,and the higher the refractive index sensitivity of the Sagnac ring with cascading FBG embedded fiber to part of the cladding.