Photonic-crystal-waveguide-assisted directional couplers for hybrid Si/GaN nanophotonics

Photonic-crystal-waveguide-assisted (PCW-assisted) directional coupler fabricated from a hybrid nanophotonic fabrication platform of Si and GaN was studied. The coupler consisted of a Si PCW stacked on top by a GaN ridge waveguide (GaN RdW). High scattered near-infrared intensity at the output ports of the coupler was observed. The maximum coupling found was around 50%. The study may be promising for complex nanophotonic systems such as optical interconnect or optical signal processors.