Two Kinds of Polarization Filter Based on Photonic Crystal Fiber With Nanoscale Gold Film

The polarization characteristics of photonic crystal fibers (PCFs) with nanoscale gold film are evaluated by using a finite element method. The coupling theory between core mode and SPP mode is introduced. Their application to fiber filter is investigated. The PCF filters for the ranges of 1.31, 1.48, and 1.55 μm and a wide wavelength range are designed. We demonstrate that the resonance wavelengths are modulated by adjusting the diameter of the air hole with gold film, and the resonance wavelengths of x-polarized and y-polarized mode are divided by high birefringence of core. By our structure, the loss of y-polarized mode is larger than the loss of x-polarized mode at the resonance wavelength. When the diameter of the air hole with gold film is big enough, the loss of y-polarized mode is further larger than the loss of x-polarized mode at the wavelength range of 1.25-2.0 μm.