Study On Temperature Sensing And Bend-Resistant Characteristics Of Photonic Crystal Fibers

Photonic crystal fiber(PCF)is a kind of two dimension photonic crystals which presents a wavelength-scale periodic microstructure running holes along their length.As a new type of the communication medium,the photonic crystal fiber has the advantages of the flexibility in structure design,new propagation mechanisms and some other excellent characteristics that the conventional fiber doesn't have.In recent years,the photonic crystal fiber has been of great interest in optical fiber communication area as it provides a new way to improve the optical fiber communication technology.Nowadays,there are a lot of researches on photonic crystal fibers.This thesis aims to investigate the temperature sensing characteristics and bend-resistant ability of the photonic crystal fiber.Through doping liquid crystals into the core region and the shaping mode of the infiltrated cores,this thesis has proposed a seven-core photonic liquid crystal fiber whose mode intensity is sensitive to the temperature.By using the full vectorial finite element method,the characteristics of this PCF are analyzed.The numerical results show that this PCF can keep single mode operation at 1.1-1.7?m,has low confinement loss and high coupling efficiency.Our designed muti-core PCF can be a good candidate for optical fiber splitters and couplers which are sensitive to the temperature.Using the full vectorial finite element method,we propose a novel kind of symmetric bend-resistant photonic crystal fiber with simultaneous achievement of large mode area and single mode operation.The numerical results show that the single mode operation and a large mode area which is larger than 1000?m~2 can be realized with a bending radius of 15cm and the wavelength of 1.064um.Compared with the existing asymmetric PCFs,the proposed PCF can not only realize the excellent bend-resistant characteristics but also have the advantage of being insensitive to the bending direction.From the above,this thesis has proposed two novel photonic crystal fibers which have great significance for temperature sensing and high power fiber devices respectively and has great research value for the design of high-performance optical fiber communication systems.