| Photonic Crystal Fiber?PCF?is a new type of fiber derived from PCF.Different from traditional fiber,Photonic Crystal Fiber has many excellent characteristics,such as high sensitivity,low limit loss,high birefringence,high nonlinearity and so on.Due to the influence of external factors and its own structure,the traditional optical fiber will be limited in many fields,unable to play its own advantages,while the photonic crystal is a periodic dielectric structure,with a high degree of design freedom,which can be achieved by adjusting the PCF microstructure parameters,changing the functional materials filled in the core and changing the background materials of the optical fiber.In recent years,high birefringence PCF?HB-PCF?has been widely used in the fields of communication,biosensor and so on.In this paper,the characteristics of several kinds of high birefringence photonic crystal fibers are studied,such as birefringence,limited loss,dispersion,sensitivity,nonlinearity,etc.Through the optimization of structural parameters,fillers and background materials,we use the finite element method to analyze the structure of the designed Photonic Crystal Fibers,and the Lumerical simulation software is used to simulate several kinds of different structures of Photonic Crystal Fibers.The simulation analysis of the characteristics of the crystal fiber has achieved good simulation results.At the same time,the transmission characteristics of the high birefringence photonic crystal fiber and the preparation process have been studied more in-depth and systematically.The main research results are as follows:?1?A kind of HB-PCF structure with elliptical core is put forward.In the actual drawing,the elliptical air hole is difficult to be successfully drawn,and the cost is high,while the circular air hole is easier to manufacture and realize.On the other hand,birefringence and other characteristics can achieve the effect of elliptical hole or even higher.By comparing and analyzing the influence of different hole spacing and air hole diameter on PCF characteristics,the optimal parameters are obtained.The calculation results show that the birefringence can reach 1.972×10-22 when the wavelength is 1.55?m,the limiting loss can be as low as1.69378×10-7dB/m,and the nonlinear coefficient can up to 54.6757W-1·km-1.?2?A HB-PCF structure based on liquid sensor is designed.The influence of ellipticity on the properties of PCF and the influence of two different liquids filled in PCF core on different characteristics of optical fiber is studied.The results of numerical analysis and optimization of the model show that when?=1.55?m and?=0.6,the birefringence values of PCF1 and PCF2 are 3.8×10-44 and 2.8×10-44 respectively,the limiting losses are1.599×10-7dB/M and 3.923×10-8dB/m respectively,the relative sensitivity coefficients are69.2519%and 72.5067%,and the nonlinear coefficients are 44.4076Km-1W-11 and46.5275Km-1W-1,respectively.According to numerical analysis,ethanol is more suitable for liquid sensing than water.According to the performance analysis,the structure proposed in this paper will provide a new idea for the field of PCF liquid sensor.?3?By using Ge15As25Se15Te455 and Ge20Sb15S655 as the base materials of HB-PCF for comparative analysis.Through changing the structural parameters to simulate and analyze the characteristics of PCF.Under the optimized parameters,the designed HB-PCF structure can achieve birefringence of 10-1 in the mid-infrared band,and also can obtain low dispersion and low loss.Sulfur glass is the only glass material with far-infrared transmittance,which has good stability.It combines the advantages of photonic crystal structure with the characteristics of chalcogenide glass material,and has potential applications in the fields of supercontinuum spectrum and optical devices. |
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