全固态反谐振光纤折射率调控特性及耦合传输的数值模拟研究OA

[Background]High-power Yb-doped fiber lasers operating in the 1 μm band have been widely applied in fields such as laser processing,biomedicine,and national defense security.However,with the continuous increase in output power,traditional large-core fibers are susceptible to transverse mode instability(TMI)and stimulated Raman scattering(SRS),among other nonlinear effects.Based on their unique anti-resonant light-guiding mechanism,all-solid anti-resonant silica fibers(AS-ARFs)can realize ultra-large mode area(LMA)propagation while suppressing higher-order modes(HOMs),thus providing an innovative technical approach for balancing high power and high beam quality.Nevertheless,for active Yb-doped AS-ARFs targeting high-power gain applications,the influence mechanism of core refractive index fluctuations on mode characteristics and the fusion-splicing transmission characteristics of"step-index fiber(SIF)-AS-ARF"structures have not been systematically investigated,which restricts their practical application.[Purpose]To address the above problems,this study aims to clarify the critical value of refractive index variation for maintaining the original light-guiding mechanism of AS-ARFs,verify their capabilities of low loss,large mode area and beam quality maintenance,explore the fusion-splicing coupling transmission characteristics between SIFs and AS-ARFs,quantify the core control parameters of active AS-ARFs,and provide theoretical support for their fabrication process optimization and coupling scheme design.[Methods]A six-ring AS-ARF theoretical model was constructed,combined with theoretical derivation and numerical simulation:Comsol Multiphysics was used to analyze the mode characteristics and the influence of refractive index fluctuations,and the Rsoft-BeamPROP module(based on the beam propagation method)was adopted to simulate the light transmission laws in the fusion-splicing coupling scenario.[Results]The critical value of refractive index variation was clarified;the designed AS-ARFs were verified to have the characteristics of low loss,large mode area and excellent beam quality at the target wavelength;the fusion-splicing coupling transmission laws were revealed,and the transmitted energy attenuation was less than 2%when the incident beam diameter matched the core diameter of AS-ARFs.[Conclusions]This study quantifies the core control parameters for active AS-ARFs,laying an important theoretical foundation for the fabrication process optimization of Yb3+-doped AS-ARFs(with a focus on refractive index uniformity control)and the design of practical coupling schemes.