In this paper, a new type of flat-band slow light structure with high group index (ng) and large normalized delay-bandwidth product (NDBP) in a silicon on insulator (SOI) based photonic crystal (PC) slab
waveguide with a triangular lattice of circular holes is demonstrated. The dispersion engineering is performed
by infiltrating optical fluids with different refractive indices nf
in the first row and shifting the second row of
air holes adjacent to the PC waveguide (PCW) in the longitudinal direction. In the optimized case, a high
NDBP of 0.32 with a group index of 54.55 and a bandwidth of 9.13 nm could be obtained. Furthermore, an
ultra-low group velocity dispersion (GVD) in the range of 10–20 s2
/m is achieved in all of the structures. These
results are obtained by numerical simulations based on three-dimensional (3D) plane wave expansion (PWE)
method.