High-Loss Dual-Channel Broadband Photonic-Crystal Fiber Polarization Filter Based on Surface Plasmon Resonance

In this paper, we propose a dual-channel broadband photonic-crystal fiber polarization filter with high loss based on surface plasmon resonance. We carefully design gold-coated elliptical air hole structure to improve the confinement loss and the isolation of x-polarized and y-polarized guided modes. Multi-order plasmonic modes are excited to broad the filtering band. Moreover, in view of our simulation results, we demonstrate that plasmonic resonance occurs at the wavelength, where birefringence abnormally changes; also, complete and incomplete mode coupling are able to be distinguished by birefringence. At communication wavelengths of 1550 and 1318 nm, the calculated confinement loss of x-polarized and y-polarized core modes are 744.63 and 1089 dB/cm, with crosstalk up to – 1282.54 and 2233.46 dB, respectively. The proposed dual-channel polarization filter will be a good choice for optical fiber communication.