Broadband Polarization Beam Splitter Based on Silicon Dual-Core Photonic Crystal Fiber with Gold Layers Operating in Mid-Infrared Band.

In response to the immediate requirements of modern high-speed and high-capacity integrated optical circuit development, this study introduces a broadband all-fiber polarization beam splitter (PBS) based on silicon dual-core photonic crystal fiber (PCF) and gold layers. Simulation results demonstrate that silicon as the substrate material is conducive to extending the operating range to the mid-infrared band of 3.0 ~ 3.6 μm. The modulation effect of the gold ring layers on the left and right sides of central elliptical hole is very impressive, and when the cladding hole diameter d1 = 1.3 μm, gold-coated hole diameter d2 = 1.8 d1 = 2.34 μm, hole-to-hole pitch Λ = 2.0 μm, gold layer thickness t = 50 nm, long axis a = 2.08 μm, and short axis b = 1.43 μm, coupling length ratio (CLR) between x- and y-polarized super-mode exactly is equal to 2. According to performance investigation by finite element method (FEM), this PBS is well suited for splitting out x-polarized light in core A, which can possess a minimum size of 0.66 mm, a maximum extinction ratio (ER) of 78 dB at 3.3 μm, a broad operating bandwidth of 450 nm, and a low insertion loss (IL) of 0.15 dB at 3.3 μm simultaneously. The proposed PBS features both high integration and high performance, which will be applicable to all-optical networks in mid-infrared fields. [ABSTRACT FROM AUTHOR]