A Novel Design of Photonic Crystal Fiber for Robust Orbital Angular Momentum Transmission

A distinct structure of photonic crystal fiber (PCF) that supports 238 orbital angular momentum modes (OAM) between 1.5 μm and 1.675 μm wavelength is proposed here. Numerical analysis by finite element method indicates better propagation characteristics that secure high-capacity optical data transmission. Due to the higher effective refractive index difference (>5.5×10−3) between the supported HEl+1,1 and EHl−1,1 modes, crosstalk between the guided modes is anticipated to be minimal. Additionally, flat dispersion enables greater light confinement in the propagation region resulting in low confinement loss (~10−13–10−9 dBm−1). The higher-order radial modes are suppressed with a narrow ring as the propagation region while maintaining a higher mode purity of over ~95%. The low nonlinear coefficient of ≤0.69 W−1km−1 indeed assures that the proposed PCF design is superior for OAM modes propagation.