Dual-window polarization filtering characteristics of rectangular photonic crystal fibers

This paper presents a photonic crystal fiber (PCF) polarization filter with a square array arrangement of gold film fillings, allowing for filtering at dual wavelengths. The paper analyzes the dispersion characteristics and loss properties of this structure and optimizes the structural parameters through adjustments to achieve the best performance. At 1310 nm, the confinement losses of x and y polarization fundamental modes are 903.54 dB/cm and 30.51 dB/cm, respectively; at 1640 nm, the confinement losses of y and x polarization fundamental modes are 479.02 dB/cm and 88.72 dB/cm, respectively. The corresponding filtering bandwidths are 390 and 350 nm, while the full width half maximum (FWHM) is 59.56 nm, indicating excellent selectivity and resolution of the filter. The performance metrics, such as confinement loss, extinction ratios, and bandwidth, are compared in the paper with those reported for other filters. Additionally, the study also analyzed the filter’s performance under varying manufacturing tolerances of gold film thickness and air hole diameter by 5%, revealing that the filter’s performance remains stable and feasible even in the presence of errors.