Anti-resonance fiber propagating 86 orbital angular momentum modes with high purity for a long distance

Future advances in information transmission technology require better capacities for fiber optics communication. As a new degree of freedom, the orbital angular momentum (OAM) has attracted extensive attention in the field of mode division multiplexing. Herein, an anti-resonance fiber (ARF) is designed with three different materials, SF11, LaSF09, and SiO₂, for the negative curvature tube. Systematic analysis and optimization are carried out to determine the number of layers of the negative curvature tubes in the cladding, the number of second-layer cladding tubes, and thickness of the annular area. The finite element analysis software COMSOL is utilized to calculate the effective refractive index difference, dispersion, limiting loss, and other characteristics. The ARF can stably transmit 86 OAM modes in the wavelength range between 1.2 and 2.0 μm, and the minimum refractive index difference is greater than 1 × 10^-4, which effectively reduces the mode abridgment. The nonlinear coefficients of the HE_23,1 mode and the OAM purity of HE_1,1 mode are 0.34km^-1⋅W^-1 and 99.43%, respectively, thus facilitating stable transmission of OAM modes for a long transmission distance. The anti-resonance fiber has significant application potential in long-distance network information transmission, relay communication, and other communication areas. © World Scientific Publishing Company.