Annular core photonic quasi-crystal fiber with wideband nearly zero ultra-flat dispersion, low confinement loss and high nonlinearity

We propose an annular core photonic quasi-crystal fiber with ultra-flat dispersion, low confinement loss and small effective mode area covering O, E, S, C, L and U bands. The proposed design has a six-fold symmetric quasiperiodic array of air holes with a central air-hole in the core (an annular core), which induce wideband nearly zero ultra-flattened dispersion of 0 ± 0.11 ps/(nm.km) from 1.15 μm to 1.65 μm, low confinement loss in level of 10−4 and the small effective mode area of 5.55 μm2 at 1.55 μm.