Design of low loss THz dual guided photonic crystal fiber with supporting of 68 OAM modes and 8 LP modes

In this work, we propose a novel dual guided PCF design capable of supporting the transmission of 68 OAM modes. The innovative design features a specialized structure with multiple layers composed of pure silica and SF57 material arranged alternately. To enhance physical strength and minimize loss, the fiber is enclosed by a perfectly matched layer (PML). Air holes are strategically added and optimized in the third and fifth layers. Through numerical analysis, we observed that the proposed design yields excellent results across all evaluated parameters. The maximum confinement loss recorded is 10-12 dB/m. The effective refractive index values range from 1.444 to 1.8, with effective refractive index difference values in the order of 10-2. Furthermore, the modal purity and power fraction values exceed 99% for all modes. Dispersion values are maintained below 9.87 ps/THz/cm, and crosstalk values are less than - 12 dB. These results demonstrate the potential of our dual guided PCF design in meeting the increasing demands for high-speed and reliable communicating systems.