Design of photonic crystal fiber for long-distance transmission of orbital angular momentum

Abstract

In this paper, a new photonic crystal fiber (PCF) for long-distance transmission of orbital angular momentum (OAM) is proposed. The rectangular air holes are distributed in the cladding and a circular air hole is distributed in the core. The designed PCF can support 88 OAM modes over S + C + L + U wavelength band. The characteristics of the PCF are analyzed by using the finite element method systematically. The results show that the nonlinear coefficient is lower than 2.8 km−1·W−1 over S + C + L + U wavelength band, and the minimum value is as low as 0.9 km−1·W−1. The confinement loss of each mode is between 10−17–10−10 dB·m−1, and the stable transmission distance of the OAM modes is up to 60 km. Additionally, the effective mode filed area and dispersion of the PCF are also analyzed. In general, the PCF can be used in modular division multiplexing which can effectively improve the capacity and transmission distance of communication system.