High Extinction Ratio and Large Bandwidth PCF Polarization Filter With Gold-Wires Coated by Monocrystalline Silicon

A kind of high extinction ratio (ER) and large bandwidth photonic crystal fiber (PCF) polarization filter based on surface plasmon resonance is proposed. The SPP modes can be inspired by two gold-wires to improve the filter characteristics and the effect of surface plasmon resonance is further enhanced by cladding monocrystalline silicon surrounding gold-wires. An asymmetric structure of leakage channel is introduced in y-pol direction axis which intensifies the energy leakage to external cladding, high polarization extinction ratio is occurred. By using the finite element method (FEM), the structural parameters and optical properties are quantitatively analyzed. Numerical analysis shows that two main adjacent resonance peaks appear in y-pol direction, confinement losses of y-pol core mode at the resonance wavelength of 1519 and 1664 nm are 573.33 and 543.21 dB/cm, while the losses of x-pol core mode are 16.97 and 0.98 dB/cm. When the fiber length L=3 mm, the maximum ER reaches 1449 dB at the wavelength of 1519 nm, and the bandwidth with ER better than 20 dB reaches 405 nm. Hence the proposed PCF with gold-wires coated by monocrystalline silicon would have a widely application in optical fiber communication, optical information processing and other fields.