Rectangular lattice photonic crystal fiber with simultaneous polarization filtering at communication wavelengths of 1310 nm and 1550 nm

In this study, we developed a tunable photonic crystal fiber (PCF) polarized filter with a gold coating and liquid filling, which was investigated using the full-vector finite-element method. The gold that selectively filled the cladding air holes acted as a defect mode. When light was transmitted into the core, the energy was transferred from the core mode to the defect mode at a given wavelength and a resonance peak was obtained. Numerical results showed that the proposed PCF could be implemented simultaneously for polarization filtering in the communication windows of 1.31 and 1.55 mu m. The confinement losses for the y-polarized mode were 251.5 dB/ cm for 1.31 mu m and 375.3 dB/cm for 1.55 mu m. When the fiber length was 90 mu m, the corresponding bandwidths were just less than 20 and 70nm for 1.31 and 1.55 mu m, respectively. The bandwidths are the narrowest obtained and they are conducive to applications in integrated systems. We also studied the effects of structural parameters on the resonance performance. The optical fiber structure could be optimized further to obtain better results.