本文基于全矢量有限元法,设计了一种V形结构高双折射光子晶体光纤,数值分析结果表明:当光纤的包层孔间距Λ为1.0μm,包层大空气孔D和小空气孔d分别为0.95μm,0.7μm时,在波长为1.55μm处,该光纤的双折射度B达到1.225×10-2,比传统光纤高约两个数量级.另外,分别在可见光和近红外波段出现了两个零色散波长,使钛宝石飞秒激光器工作波段(700—980nm)处于光纤的反常色散区,为新颖的光子晶体光纤非线性效应研究提供了理论基础;同时,其快轴与慢轴空气填充率的巨大差异也使得这种高双折射光纤对微型传感器件的研制有着重要的应用.
According to the full-vector finite element method, a new kind of V-shape photonic crystal fiber with high birefringence is proposed. Simulation results show that the V-shape photonic crystal fiber has a birefringence of 1.239×10-2 at a wavelength of 1.55 μm, when its cladding air hole pitch, large air hole diameter, small air hole diameter are 1.0 μm, 0.95 μm and 0.6 μm, respectively. There are two zero dispersion wavelengths in the visible and the near-infrared region respectively, and the abnormal dispersion zone includes the operation wavelength of Ti:sapphire laser, which is advantageous for nonlinear generation of photonic crystal fibers. The difference in air filling fraction between fast and slow axis can be used as a sensor for the weak strain.