Polarization-dependent coupling characteristics of metal-wire filled dual-core photonic crystal fiber

We theoretically investigate a dual-core photonic crystal fiber filled with metal wire. The metal wire is filled into the air-hole between the two cores. The surface plasmon polarizations excited on metal wire present strong polarization-dependent coupling to the core modes in the dual-core photonic crystal fiber. Numerical simulations demonstrate that the coupling lengths show obvious reduction compared to conventional dual-core photonic crystal fibers. By the appropriate selection of the fiber parameters, a novel polarization splitter with extinction ratio lower than dB over a 250-nm wavelength can be realized.