Delay bandwidth product enhanced slow light in photonic crystal waveguides

In this paper, we propose photonic crystal waveguide structure to attain enhanced slow light performances by carrying out various optimizations on a regular triangular lattice photonic crystal. While residing at a moderate slow down factor (group index), the investigated structure provides a very large delay bandwidth product factor. This value outperforms the previously declared numbers available in the literature. For a particular formation of the structure, the normalized delay bandwidth product (n-DBP) reaches to 0.618. The primitive structure is a triangular lattice photonic crystal with air holes in dielectric background. Waveguide is obtained by reducing radii of particular holes lying on a line and shifting these holes in the propagation direction. Then by changing the radii of background holes, the dispersion relation of the relevant mode is engineered to maximize n-DBP value. Various dispersion formations are obtained that show outstanding performances with respect to the previously published studies. The investigated slow light structures can be very desirable while designing optical buffers, nonlinear optics and highly sensitive biochemical sensors.