The Effect of Incomplete Coupling on Slow Light Propagation in Ring-shape-hole Photonic Crystal Waveguide

In photonic circuits, the substrate optical connections are usually realized by the Rib waveguides. The effective coupling between the slow light waveguides and the Rib waveguides is a major challenge which has been an interested research topic. Previously, several researches were conducted on the effective coupling while the incomplete coupling effects on the slow light propagation in the Photonic Crystal Waveguides (PCW) are not investigated so far. In this paper, an optimized structure of the ringshape-hole PCW is utilized in order to investigate the effects of incomplete coupling on the slow light propagation. The simulation results show that a considerable portion of the propagation losses is caused by the incomplete coupling. On the other hand, the superposition of the waves reflected to the waveguide causes the irregular behavior of slow light. According to results, this phenomenon affects the calculation of the loss and the group index.