Tunable single-polarization bimetal-coated and liquid-filled photonic crystal fiber filter based on surface plasmon resonance

A bimetal-coated single-polarization photonic crystal fiber (PCF) filter based on surface plasmon resonance (SPR) with a liquid-filled structure is designed and calculated by the finite element method (FEM). The filter has many excellent properties. The y-polarized and x-polarized modes can simultaneously filter at 1310 nm and 1560 nm with unwanted losses 544.3 dB/cm and 147.3 dB/cm, respectively, corresponding to polarized losses as low as 12.3 dB/an and 24.0 dB/cm. The filtering range can be tuned by adjusting the diameter of the outer air holes (d₁), the diameter of the inner air holes (d₂), and liquid refractive index n. The filtering ranges of x-polarization and y-polarization are 1550-1990 nm and 1310-1830 nm, respectively. The crosstalk (CT) values are 462.0 dB and -107.1 (113 and corresponding available bandwidths are 224 nm and 504 nm at 1310 nm and 1560 nm, respectively.