Efficient and compact coupling to slow light structures

In this study, we present several coupling structures designed for two different slow light photonic crystal waveguides (PCW). These slow light structures provide group indices of approximately 1200 and 950. For the first waveguide, very high coupling efficiency of 97% is declared from/to conventional waveguide to/from slow light PCW. The improvement lies on the optimization of the tapered input/output transition sections. Another novel coupling scheme for the second waveguide is proposed.