Efficient light coupling from integrated single-mode waveguides to supercollimating photonic crystals on silicon-on-insulator platforms

We propose a practical and efficient solution for the coupling of light from integrated single-mode waveguides to supercollimating planar photonic crystals (PhCs) on conventional silicon-on-insulator platforms. The device consists of a rib waveguide, designed to sustain spatially extended single modes and matched to a supercollimating PhC, which has been truncated at its boundary to improve impedance matching between the two photonic components. Three-dimensional simulations show transmission efficiencies up to 96% and reflections below 0.2% at wavelengths close to 1.55μm. This approach constitutes a significant step toward the integration of supercollimating structures on photonic chips.