Slow Light Property Improvement and Optical Buffer Capability in Ring-Shape-Hole Photonic Crystal Waveguide

Flatband slow light in a ring-shape-hole photonic crystal waveguide (RPCW) has been theoretically investigated. Numerical results show that both the outer and inner radii of the first two rows of holes adjacent to the defect have much affect on slow light properties. Therefore, by appropriately modifying the outer and inner radii of the ring-shaped holes, the slow light property is successfully optimized. Then we further enlarge the flat bandwidth by introducing the oblique structure. The negligible dispersion bandwidths ranging from 3.57 to 24.67 nm for group indexes from 28 to 115 are obtained, respectively, which is effectively improved if compared with other RPCW structures in previous works. Moreover, we also discussed the buffer capability and signal transmission characters of the RPCW. The result shows that the proposed structure has considerable potential for optical buffering applications.