Femto-joule threshold reconfigurable all-optical nonlinear activators for picosecond spiking neural networks

Achieving optical computing with thousands of tera-operations per second per watt per square millimeter (TOPs/W/mm ² ) is the key to surpassing electrical computing. This realization requires a breakthrough in the design of a new optical computing architecture and nonlinear activation functions. In this work, we propose an on-chip picosecond spiking optical neural network architecture, which can be expected to achieve 2.13×10 ³ TOPs/mm ² . By leveraging the Kerr effect of silicon and the saturable absorption of graphene, we designed an all-optical nonlinear activator based on a graphene-silicon integrated photonic crystal cavity. The ultralow threshold, high-speed, compact, and reconfigurable all-optical nonlinear activator could achieve a 4 fJ activation energy threshold, a 1.05 ps response time, and an ultrasmall size of 15 µm×10 µm. This device provides foundation blocks for the picosecond spiking optical neural network chip to achieve 10 ⁶ TOPs/W/mm ² level optical computing.