Mode matching technique for highly efficient coupling between dielectric waveguides and planar photonic crystal circuits

In this paper, a mode matching technique for highly efficient coupling between dielectric silica waveguides (SWG) and planar photonic crystal (PPC) waveguides based on setting localized defects in a PPC tapered waveguide is reported. The introduction of multiple defects is designed properly depending on mode mismatching arising from the different widths of the SWG and the PPC waveguide. The procedure to obtain the optimum defects configuration is described. Transmission efficiencies above 80% at a wavelength of 1.55mum are reported improving significantly the transmission efficiencies achieved with conventional PPC tapered structures without defects. Furthermore, the feasibility of the coupling technique for both input/output coupling over a large frequency band is shown. (C) 2002 Optical Society of America.