Ultra-wide bandwidth polarization filter based on gold-coated photonic crystal fiber around the wavelength of 1.55 µm

A novel ultra-wide bandwidth photonic crystal fiber (PCF) polarization filter based on surface plasmon resonance (SPR) is proposed. The PCF has two large cladding air holes in the direction of y-axis that are selectively coated with gold films to create resonance. There are two small holes in the direction of x-axis, which provides high birefringence. The polarization characteristics of PCF are studied by finite element method (FEM). The numerical simulation results indicate that the loss of y-polarized core mode is 718.87 dB/cm, while the loss of x-polarized core mode is only 0.95 dB/cm at the resonant wavelength of 1.55 µm. The extinction ratio is better than 20 dB at the wavelength ranging from 1.43 to 1.79 µm, the corresponding bandwidth is 360 nm.