Ring-Core Photonic Quasi-Crystal Fiber With 34 Polarization Multiplexing Modes

We propose a ring-core photonic quasi-crystal fiber (RC-PQCF) featuring a ring-shaped fiber core and two symmetrical SiO2 stress-applying parts (SAPs). By optimizing the mole percentage of GeO2 and geometrical parameters of the fiber, the design supports 34 full vector polarization modes (FV-PMs). The effective refractive index difference ($\Delta {n_{eff}}$) of adjacent FV-PMs is larger than $1.07 \times {10^{ - 4}}$ at 1550 nm. The confinement loss (${\mathrm{\alpha }}$) of FV-PMs is less than ${10^{ - 6}}$, which is sufficient to confine the light field in the ring-core. Through numerical analysis, broadband performance is investigated subsequently in the 1500–1600 nm. The dispersion (${D_\lambda }$) of FV-PMs is less than $138.14{\mathrm{\ ps}} \cdot {\mathrm{n}}{{\mathrm{m}}^{ - 1}} \cdot {\mathrm{k}}{{\mathrm{m}}^{ - 1}}$ and maintains a flat trend. The mode field area (${A_{eff}}$) of FV-PMs is larger compared to single mode fibers and the nonlinear coefficient (${\mathrm{\gamma }}$) of FV-PMs is within ($6.97 \times {10^{ - 4}}$, $1.54 \times {10^{ - 3}}$) ${{\mathrm{m}}^{ - 1}} \cdot {{\mathrm{W}}^{ - 1}}{\mathrm{\ }}$ in the 1500–1600 nm. The fiber is a promising design for mode division multiplexing (MDM) that supports the MIMO-free processing and improves the transmission capacity and spectral efficiency.