Multi-planar amorphous silicon photonics with compact interplanar couplers, cross talk mitigation, and low crossing loss

We propose and experimentally demonstrate a photonic routing architecture that can efficiently utilize the space of multi-plane (3D) photonic integration. A wafer with three planes of amorphous silicon waveguides was fabricated and characterized, demonstrating <3×10−4 dB loss per out-of-plane waveguide crossing, 0.05±0.02 dB per interplane coupler, and microring resonators on three planes with a quality factors up to 8.2×104. We also explore a phase velocity mapping strategy to mitigate the cross talk between co-propagating waveguides on different planes. These results expand the utility of 3D photonic integration for applications such as optical interconnects, neuromorphic computing and optical phased arrays.