High-birefringence photonic crystal fiber polarization filter with gold-coated and liquid-filled air holes based on surface plasmon resonance

Abstract

A high-birefringence photonic crystal fiber polarization filter is proposed. The coupling theory is used to explain full and incomplete couplings. The resonance point can be adjusted to the communication band by optimizing the fiber structure parameters. Numerical simulation results indicate that the resonance strength can reach 924.96 and 710.28 dB.cm−1 at the communication wavelength of 1.31 and 1.55 μm in x- and y-polarized directions, respectively. By filling liquid analyte, the confinement loss can reach 804.52 dB.cm−1 at the wavelength of 1.55 μm. Furthermore, when the fiber length of L equals 500 μm, the peak value of the cross talk (CT) can reach 389.15 and −280.52 dB, respectively. When the length of the fiber L equals 200 μm, the bandwidth of the CT better than 20 dB is up to 120 nm at the wavelength of 1.31 μm, and the bandwidth of the CT<−20 dB is up to 140 nm at the wavelength of 1.55 μm. These properties make it a good candidate for designing types of polarization filter devices.