Research On Design And Analysis Of Chalcogenide High Birefringence Photonic Crystal Fiber In Mid-infrared

Compared with silica glass,Chalcogenide glass has a lower softening temperature,good fiber forming performance and high nonliner refractive index,and are transparent in near infrared and middle infrared.Chalcogenide glass photonic crystal fiber have attracted many attentions recently,it can break the limit of transmission window below 2?m with tradition silica,and has widely applications in infrared fiber sensing,fiber optical pulse laser and all-optical-network.This thesis aims to design newly kinds of HB-PCF(High Birefringence-Photonic Crystal Fibers)and SPSM-PCF(Single Polarization Single Mode-Photonic Crystal Fiber)apply for mid-infrared(3?5 ?m),to study the birefringence,efffective refractive index,beat length,dispersion,confinement loss,nonlinearity of the HB-PCF and the single mode properties of the SPSM-PCF.Three kinds of novel HB-PCF based on Ge20Sb15Se65 glass are designed,including V-type ellipse HB-PCF structure,rhombic holes HB-PCF structure,circle cladding with micro rhombic HB-PCF structure.Numerical calculation of the HB-PCF by using FDTD method are investigated and optimized its structural parameters.Numerical results show that V-type ellipse HB-PCF has a birefringence of 0.1177 at wavelength of 5?m when the structure parameters setting as ?=1.7?m,b=0.85?m,a1=0.5?m,a2=0.28?m;rhombic holes HB-PCF has birefringence of 0.1513,nonlinearity of 3726w-1km-1?2585w-1km-1 for x-polarization and y-polarization at wavelength of 5?m,respectively.For circle cladding with micro rhombic HB-PCF,the range of the birefringence is 0.1677?0.1637 while the range of the wavelength is 3?5?m when the structure parameters setting as d=2.2?m??=2.2?m?d1=0.1 ?m?d2=0.16?m?A'=0.40?m.The proposed HB-PCF all belongs to high birefringence level,which provides a reference for studying HB-PCF with new background material.Because of the polraization ability of HB-PCF is affected by the polarization crosstalk and polarization dispersion,two kinds of novel SPSM-PCFs based on Ge20Sb15Se65 glass are proposed,rhombic SPSM-PCF and circle holes rectangular lattice SPSM-PCF.The effective refractive index,single mode characteristic and confinement loss of the SPSM-PCF by using FDTD method are investigated.Numerical results show that for the rhombic SPSM-PCF,single-polarization operation wavelength range can be 2.9662?m(4.0338?m?7.00?m)when the structure parameters setting as ?=2.6?m,D1=2.2?m,d1=0.4?m,D=2.4?m,d=1.2?m,and only x-polarization mode can been guided.For the circle holes rectangular lattice SPSM-PCF,the single-polarization operation wavelength range can be 2.3814?m(3.161?m?5.5424?m)when the structure parameters setting as ?=2.0?m,d=1.4?m,D=1.64?m,a=1.7?m,b=1.2?m,and only y-polarization mode can be transferred.It provides theoretical basis for fabrication of SPSM-PCF with simple structure and good performance.