Zero dispersion slow light with low leakage loss in defect Bragg fiber

By introducing a defect layer into the periodic cladding of Bragg fiber, the core mode and the defect mode may anticross near their cutoff inside band gap. The defect location suppresses and flattens dramatically the group velocity (vg) of coupled core mode and the defect thickness changes gradually its dispersion. Theoretical investigation reveals zero dispersion and zero dispersion slope at various low vg’s can be achieved simultaneously at arbitrary wavelengths. Specially, the proper defect in the sixth bilayer leads to the lowest vg of 0.074 of light speed in vacuum at 1550nm. The optical energy is confined well in the core and the leakage loss is sufficiently low.