High-performance dual-core photonic crystal fiber polarization beam splitter based on gold-titania composite film coating

Abstract A novel gold-titania composite film-coated dual-core photonic crystal fiber polarization beam splitter (GT-DC-PCF PBS) is proposed for the first time. The titania film and gold film are sequentially deposited on the inner wall of the central air hole to improve the polarization splitting performance and enhance the adsorption strength between the gold film and the optical fiber. Based on the mode coupling theory and surface plasmon resonance effect, the transmission characteristics of x-polarization (X-pol) and y-polarization (Y-pol) odd and even modes in the near-infrared band are analyzed by finite element method. Meanwhile, the variation of coupling length and coupling length ratio for X-pol and Y-pol light under different PCF structural parameters at the wavelength of 1550 nm are also studied to optimize the performance of PBS. The results show that at the 1550 nm communication window, the extinction ratio of the PBS is up to −175.82 dB for the polarization splitting length of 2.76 mm, with an operating bandwidth of 179 nm and a maximum insertion loss of 0.23 dB. This paper aims to propose a novel design method to improve the performance of DC-PCF PBS, which has profound guiding significance for the development of high-performance PBS.