Design of a multi-core photonic crystal fiber supporting 518 OAM modes

A multi-ring core photonic crystal fiber (PCF) with seven high-index ring regions is designed for the transmission of multiple orbital angular momentum (OAM) modes. The new structure which has an optimized air hole arrangement shows improved transmission quantity and number of OAM modes. Numerical analysis reveals that the PCF can transmit 518 OAM modes in the range of 1.4–1.75 µm stably while avoiding cross talk from the adjacent ring core resulting in a low cross talk of merely −208.5dB, confinement loss less than 10 −9 dB/m, as well as mode quality greater than 0.925. The results disclose a new method to increase the communication capacity and suggest that the PCF has great application potential.