Photonic crystal fiber for supporting 26 orbital angular momentum modes.

We propose and numerically investigate a photonic crystal fiber (PCF) based on AsS for supporting the orbital angular momentum (OAM) modes up to 26. The designed PCF is composed of four well-ordered air hole rings in the cladding and an air hole at the center. The OAM modes can be well separated due to the large effective index difference of above 10 between the eigenmodes and maintain single-mode condition radially. In addition, the dispersions of the modes increase slowly with wavelengths, while the confinement loss keeps as low as 10 dB/m. The proposed PCF increases the supported OAM modes which could have some potential applications in short-distance, high-capacity transmission.