Study On Double-Cladding Yb³⁺-Doped Photonic Crystal Fiber With High Numercial Aperture

Photonic crystal fibers has been of extensive interest to researchers due to single mode operation,large effective area,tunable dispersion,highly nonlinear performance compared with ordinary optical fibers and broad application prospects.Yb³⁺ -doped double-clad photonic crystal fibers with high NA was designed and prepared in this paper.The sample is suitable for the development of high-power lasers due to its high doping ratio for Yb³⁺ ion,large stimulated emission cross section,emission bandwidth,higher pump power resistance and higher temperature resistance.Yb³⁺-doped silicate laser glasses(45.27SiO₂,19.98B₂O₃,32.75M_xO_y(K₂O,Li₂O,BaO,ZnO,La₂O₃),2Yb₂O₃(mol%)) was prepared using the melt quenching technology in this paper.The stimulated emission cross section and the potential laser performance of sample were calculated by using the absorption spectra and the McCumber theory.The fluorescence efficiency linewidth was 83.23nm.The fluorescence lifetime was 1.13ms.The minimum pump power is 1.82 kW/cm².The Zero-gain required minimum number of excited particles is 0.169.The completed pump power is 10.8 kW/cm².The Yb-doped silicate glass photonic crystal fiber is a better mandril material showed the performance.The hexagonal photonic crystal fiber whose∧is 1.02～10.2μm,d/∧is 0.38,n_cladding is 1.5167,n_core is 1.5823 was designed in this paper.Based on finite element theory,the inner cladding structure of the designed photonic crystal fiber was numerical simulated by using the COMSOL Multiphysics software.The Yb-doped photonic crystal fiber whose the hole spacing∧=10.2μm,d/∧=0.38,n_core=1.5823,n_cladding=1.5808 Was numerical simulated, obtained the effective refractive index n_eff is 1.581481 whenλ=1020nm,and the effective mode field area of fundamental mode A_eff is 95.1μm² without the appearance of second-order model.Based on the result of numerical simulation,the micro-structure photonic crystal fibers was prepared by using the rod tube stacking method.