Ultra-broadband Polarization Filter Using Liquid-Infiltrated Dual-Core Photonic Crystal Fiber and Surface Plasmon Resonance
摘要
In this paper, we propose a single polarization filter to regulate the polarization state of signal light by exploiting the high birefringence properties of photonic crystal fibers (PCFs). A two-core PCF filter based on a liquid filled with an elliptical gold hole was numerically simulated using the finite element method (FEM). The results show that the PCF filter demonstrates excellent filtering performance near the 1310 nm communication window with an air hole diameter d of 2.0 µm, a pore spacing Ʌ of 2.5 µm, a gold film thickness t of 30 nm, an elliptical hole axis da of 2.0 µm, and an axis db of 2.6 µm. The liquid of refractive index 1.36 was filled into the central air hole. The peak resonance loss strength is as high as 1008.15 dB/cm for the x-polarized mode, while it is only 39.16 dB/cm for the y-polarized mode. Moreover, the crosstalk and operation bandwidth increase with the fiber length. When the PCF transmission length reaches 400 µm, the maximum crosstalk can reach − 335.54 dB and the bandwidth can reach 550 nm. The photonic filter is expected to be widely used in optical communication, optical sensing and other fields.