A high crosstalk modified D-shaped single-polarization filter for S and U band optical communication

This manuscript has analyzed a gold-coated photonic crystal fiber-based single-polarization filter with D-shape for a span of wavelength from 1.408 to 1.652 mu m with particular applications in S + U bands. An asymmetric arrangement of air holes has been adopted to allow high birefringence and cross-talk. The filter displays strong filtering characteristics, having a significant confinement loss of 1682.5 dB/cm for the x-direction at a 1.652 mu m wavelength while simultaneously possessing a very low intensity in the y-polarization at only 85.89 dB/cm. Additionally, its cross-talk can reach up to 1387 dB, with a 160 dB extinction ratio at a higher wavelength of 1.652 mu m for a fiber length of 1000 mu m. Thus, the filter can be utilized for both the electromagnetic spectrum's S and U optical bands.