Ultra-compact high efficiency and low crosstalk optical interconnection structures based on inverse designed nanophotonic elements.

In this paper, we combine inverse design concept and direct binary search algorithm to demonstrate three ultra-compact high efficiency and low crosstalk on-chip integrated optical interconnection basic devices in the entire wavelength range of 1,400-1600 nm based on silicon-on-insulator platform. A 90-degree waveguide bend with a footprint of only 2.4 × 2.4 μm is designed, whose transmission efficiency up to 0.18 dB. A waveguide crossing with a footprint of only 2.4 × 2.4 μm is designed, which can provide insertion loss of less than 0.5 dB and crosstalk (CL) of lower than - 19 dB. A same direction waveguide crossing with footprint of only 2.4 × 3.6 μm is designed, which can provide the insertion loss of less than 0.56 dB and the crosstalk of lower than - 21 dB. Then, we use them to form several ultra-compact optical interconnect basic structures and performed the simulation calculation. They overall achieve high performance. This will significantly improve the integration density.