Design for Terahertz Circular-Core Photonic Crystal Fiber Supporting Orbital Angular Momentum Modes

Abstract

We propose a new terahertz fiber based on a circular-core photonic crystal fiber (PCF) structure to support high-performance orbital angular momentum (OAM) modes transmission. The modal characteristics of the proposed terahertz fiber were thoroughly analyzed to vary the parameters of air holes radius and the annular thickness by the full-vector finite element method (FEM). The optimal parameters are selected to realize the stable transmission of five-order OAM mode with high mode quality, low confinement loss and wide bandwidth. The mode purity is in excess of 91%, and the confinement loss is less than 10−7 dB/m over the 0.2 THz to 0.55 THz band. Furthermore, the design of this PCF is relatively simple and flexible, since it consists only of circular air holes. Due to its excellent transmission characteristics, the proposed OAM fiber has a potential application in terahertz mode division multiplexing (MDM) communication system.