Design and Analysis of a Microstructure Ring Fiber for Orbital Angular Momentum Transmission

In this paper, we propose a novel microstructure fiber with annular core for transmitting optical orbital angular momentum (OAM), and the OAM modes are calculated under different structure parameters of the fiber. Compared with the previous hollow step-index ring fiber, the proposed fiber brings higher refractive index contrast between the ring core and the cladding region by using only the single material of silica. The designed fiber can support more well-separated OAM modes with both thin and thick rings. Simulation results show that the novel microstructure ring fiber is promising to be applied in fiber-based OAM multiplexing in order to improve communication capacity.