Theoretical Design Of Microstructured Optical Fibers And Research On The Structural Fusional Dual-parameter Sensor

Since Micro-structured Fiber(MOF)was first successfully prepared in 1996,it was widely concerned by scholars at home and abroad for its excellent properties that its internal structure can be flexibly design to achieve non-cut-off single mode and large mode area.At present,the application research of MOF has been extended to many important fields such as optical communication,optical sensing,photoelectric detection,optical fiber laser and optical medical device.As the field of application expands,the development of high and new technology has made it an urgent need to develop all kinds of high performance microstructure fiber and new microstructure fiber devices.Therefore,the development of MOF's internal structure design and new sensor theory research has important academic value and broad application prospects.This thesis uses finite element analysis to establish a theoretical model,structure parameter aperture and hole spacing of the proposed MOF impact on birefringence are analyzed in detail;The new microstructured optical fiber is filled with temperature sensitive liquid to realize temperature sensing;A novel dual-parameter optical fiber sensor based on long-period fiber grating and photonic bandgap fiber fusion is proposed The main research contents are as follows:(1)A novel high birefringence equal diameter circular-hole photonic crystal fiber which can reduce the difficulty of the drawing process is proposed,using Comsol Multiphysics to excute numerical simulation and analyzing the effect of aperture and hole spacing on the birefringence of the designed fiber.Through the choice of air hole spacing and diameter,the birefringence at the wavelength of 1550nm can reach the order of 10-3.The designed optical fiber has a simple structure,all of which are round holes,and the degree of deformation is small during the drawing process,it is a design of a highly birefringent optical fiber that conforms to the actual drawing.Selective filling of temperature-sensitive liquid for this novel microstructured fiber achieves Sagnac interference effect,the Sagnac interference effect was achieved by the selective filling of temperature-sensitive liquids on the novel microstructured fiber,and the temperature sensing characteristics of the novel fiber were analyzed and calculated,and the sensitivity was high.(2)A new type of fiber-optic dual-parameter sensor is designed.The sensor is composed of a cascade of long-period fiber gratings and photonic bandgap fibers,which realizes simultaneous measurement of temperature and strain on an optical fiber and resolves cross-sensitive interference.Temperature and strain response experiments were carried out on the optical fiber sensor,the sensitivities of the photonic bandgap fiber and the long-period fiber grating were measured to be-6.32133 nm/? and 0.04053 nm/?.The strain sensitivities were-0.13162 nm/N and-0.23183 nm/N,respectively.Through the dual parameter sensitivity matrix,we can measure temperature and strain at the same time.