Dispersion Engineering of Slow Light in Ellipse-Shaped-Hole Slotted Photonic Crystal Waveguide

Wideband slow light in an ellipse-shaped-hole slotted photonic crystal waveguide (ESPCW) has been theoretically demonstrated. By adjusting the length of major and minor axes of air holes and tuning the holes position of the second row adjacent to the slot, the group index and bandwidth of slow light can be engineered effectively at the same time. Through the optimization of ESPCW structures by the plane wave expansion (PWE) method, the nearly constant group indices at 46, 80.7, and 215.5 are obtained, and we accordingly attain the flat bandwidths of 4.81, 2.66, and 1.02 nm around the operating frequency of 1550 nm, while the variation of each group index is restricted within ±10% range. Meanwhile, the normalized delay-bandwidth product stays around 0.14, with minimal dispersion on the order of 10 ⁶ps ²/km for all the cases.