PHOTONIC INTEGRATED CIRCUIT STRUCTURE WITH COUPLER FOR INTERLAYER WAVEGUIDE COUPLING

Disclosed is a photonic integrated circuit (PIC) structure including a first waveguide core with a first end portion, a second waveguide core with a second end portion overlaying and physically separated from the first end portion, and a coupler configured to facilitate low-loss optical signal transmission between the waveguide cores. The coupler can include at least one array of photonic material elements (e.g., photonic crystal elements or photonic metamaterial elements) embedded in cladding material between the end portions. Alternatively, the coupler can include at least one photonic material layer (e.g., a photonic crystal layer or a photonic metamaterial layer) between and physically separated from the end portions and an array of cladding material elements extending through the photonic material layer. Also disclosed is a PIC structure including an on-chip system (e.g., a photonic computing system) including a crossing array implemented using any of the above-described couplers.