Photonic crystal fibers confining light by both index-guiding and bandgap-guiding: hybrid PCFs.

We propose two kinds of hybrid photonic crystal fiber (PCF) structures and investigate the properties of such PCFs in detail. The modal effective index, mode field area, confinement loss, group velocity dispersion, and birefringence are numerically simulated and compared with those of the corresponding index-guiding and bandgap PCFs, which allows for a deeper understanding of the guiding mechanism of the hybrid PCFs. The advantages of hybrid PCFs and potential applications are also discussed.