Ultrabroadband polarization filter based on gold-coated photonic crystal fiber with high birefringence is proposed and analyzed by using the finite-element method. An elliptical central air hole is designed for high birefringence and shifting the wavelength of the loss peak. The gold layers are selectively coated on the inner surface of two elliptical air holes to support the surface plasmon resonance, which contributes to the filtering characteristics. By optimizing the structural parameters, a high extinction ra2tio is obtained of about 290.56 dB at a communication wavelength of 1310 nm when the length of $L = {400}\;\unicode{x00B5}{\rm m}$, and its bandwidth is ${\sim} {530}\;{\rm nm}$. In addition, the birefringence can reach near 0.004 at 1310 nm.

中文翻译：

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基于高双折射镀金 PCF 的超宽带偏振滤光片

提出了基于高双折射镀金光子晶体光纤的超宽带偏振滤光片，并采用有限元方法进行了分析。椭圆形中心气孔设计用于高双折射和移动损耗峰值的波长。金层选择性地涂覆在两个椭圆形气孔的内表面以支持表面等离子体共振，这有助于过滤特性。通过优化结构参数，当长度$L = {400}\;\unicode{x00B5}{\rm m}$ 时，在1310 nm的通信波长下获得了约290.56 dB的高消光比，及其带宽是${\sim} {530}\;{\rm nm}$。此外，双折射在 1310 nm 处可达到接近 0.004。