Numerical analysis of a photonic crystal fiber for supporting 76 orbital angular momentum modes

We firstly propose a PCF structure with semicircular air holes. We focus on investigating the properties of the PCF based on silica. It can support 66 OAM modes from the wavelength of 1.1μm to 1.7μm with most modes' confinement losses keeping as low as 10-9dB/m. The eigenmodes effective refractive index seperation (Δneff) between HEm+1, 1 mode and EHm-1, 1 mode are above 10-3. All the nonlinear coefficients are less than 4w-1/km and the minimum value is as low as 1.4w-1/km. The minimum value of chromatic dispersion is as low as 31.8ps/(nmkm) at 1.55μm. Meanwhile, we also investigate the proposed configuration with multiple background materials. Among all the selected background materials, the numbers of supporting OAM modes range from 64 to 76. Most values of Δneff between HEm+1, 1 and EHm-1, 1 (m=2-17) modes can be kept above 10-3. The results indicate the designed configuration possesses great communication performance and material availability.