Design tool for circular photonic crystal fibers supporting orbital angular momentum modes

We propose a design tool for the family of circular photonic crystal fiber (C-PCF) supporting orbital angular momentum modes. The calibrated normalized parameters for the C-PCF family are presented. The information about the cutoff condition of modes, the number of modes supported in fibers, and the effective index difference between adjacent modes can be obtained by using the design tool. Also, the mode properties, such as confinement loss, effective mode area (A_eff), and spin-orbital coupling are analyzed using the design tool. At the end of paper, we also give some fiber design examples by using the design tool.