Research On Mode Calculation And Refractive Index Sensing Simulation Of Polarized Photonic Crystal Fiber

Computer simulation technology is a comprehensive technology which establishes a simulation system model through computer technology and analyzes the model under specific conditions.The whole simulation process is controlled by computer,and the optimal sensing scheme is obtained by analyzing and processing dif ferent simulation situations,which has high controllability.However,due to the high cost,complicated parameter adjustment process and the uncontrollable accuracy of the experiment,it is impossible to obtain better sensing performance during the experiment in a short time.Therefore,the application of computer simulation technology to the simulation of the performance of the optical fiber sensor can increase the operability of the experiment,save manpower and material resources,and provide the best guidance plan for its practical application.Based on the research of simulation technology,the paper simulates the sensing performance of three photonic crystal fiber refractive index sensors.The main research include three following aspects:1.A twin-core photonic crystal fiber is proposed and designed.The core is introdu ced into a rectangular hole array to make it have high polarization characteristics.The birefringence characteristics and refractive index sensing performance of the model w ere calculated by the finite element method.The simulation results show that the dual-parameter demodulation method based on the birefringence and wavelength of the high birefringence characteristic point can make the sensor obtain a high refractive index sensing sensitivity of 1.809×10^-2 B/RIU and 8700 nm/RIU in a wide refractive index range of 1.33 to 1.41.2.A center-symmetric four-layer hexagonal photonic crystal fiber was proposed and designed.The symmetric structure of the fiber was changed through five different selective filling methods,and the theoretical model of refractive index sensing under each filling mode was established,and optimization experiments were carried out by changing the diameterof the air hole in the cladding.Thesimulation results showthat the maximum dual-parameter sensing sensitivity of 3.134×10^-2 B/RIU and 7.15×10^-3m^-1/RIU can be obtained under the AS₃ filling mode.3.A highly birefringence photonic crystal fiber is proposed and designed.Six large air holes are introduced into the cladding area to make the fiber have obvious birefringence tunability.The finite element method is used to calculate the optical fiber mode characteristics and refractive index sensing characteristics under three different large air hole filling methods.The evolution law of the strongest polarization point shows that the optimal refractive index sensing sensitivity of 6.957×10^-2B/RIU and 16800nm/RIU can be obtained within a wide refractive index range of 1.33-1.41 under the S₂ filling mode.