Structure Design And Characteristics Research Of Photonic Crystal Fibers Based On SPR And SBS Effect

Owing to its ability of breaking the inherent limitations in conventional fibers and achieving remarkable optical performance,photonic crystal fiber?PCF?has attracted numerous attentions and been widely used in applications like high-power fiber laser and amplifier,supercontinuum light generation,fiber sensing and dispersion control system.The optical performance of a PCF is strongly dependent on its structure design.However,in the determination of the final PCF design for different application scenarios,the experimental methods are usually expensive and time-consuming.Thus for the purpose of eliminating these limitations,it is of great significance to simulate the PCF structure and numerically explore the influences of structural parameters such as background material,air hole arrangement,air hole size and hole-to-hole pitch on the optical properties of PCF.For the application scenarios of surface plasmon resonance?SPR?and stimulated Brillouin scattering?SBS?,in this thesis we designed different PCF structures and numerically studied the effects of the structure parameters on the PCF properties to improve the corresponding performance.The main work completed in this thesis include:?1?Based on SPR effect,a D-shaped PCF-SPR sensor with an open-ring channel for low refractive index detection is proposed and numerically studied.In this structure,the open-ring channel coated with gold film can not only reduce the coating area and simplify the fabrication process,but also create two passageways to enhance the resonance effect and improve the sensitivity.Numerical results indicate that the sensor has a sensing range from1.20 to 1.29.The maximum spectral sensitivity of 11055 nm/RIU and high resolution of 9.05×10^-6 RIU can be obtained at 1.29.?2?Based on SBS effect,the modeling and simulation methods of the SBS effect in PCFs are introduced and verified.Through a full-modal analysis of optical and acoustic modes in the double-clad As₂Se₃ PCF,the SBS properties is analyzed,and the effects of the structure parameters on the Brillouin gain spectra are investigated.According to the simulation results,the Brillouin gain spectrum of our proposed chalcogenide PCF exhibits a multipeaked behavior and has a high Brillouin gain coefficient,which is about 320 times higher than that of pure silica PCFs.With the increase of the inner cladding air-hole size or the decrease of the hole-to-hole pitch,the Brillouin threshold of the PCF begins to decrease,the SBS effect is enhanced,and a more pronounced second peak can be found in the Brillouin gain spectra.On the other hand,the size of the outer cladding has nearly no effect on the Brillouin gain spectra.