Simple ring-structured photonic crystal fiber with low nonlinear coefficients and flat dispersion supporting 166 OAM modes

A simple ring-structured photonic crystal fiber (PCF) is designed to support the stable propagation of multiple orbital angular momentum (OAM) modes. The PCF is numerically analyzed and optimized by the finite element method. The results show that the number of OAM modes supported by the PCF reaches 166 in the wavelength range of 1.4 to 1.7 μm. Meanwhile, the confinement loss of the OAM modes is lower than 10 − 8 dB / m, and the smallest dispersion variation is 12.7 ps / ( km · nm ) . Moreover, the mode quality of all of the eigenmodes is higher than 94.1%, and the nonlinear coefficient is lower than 0.7 w − 1 / km. The simple PCF structure with excellent properties has immense application prospects in high-capacity OAM communication.