All-optical digital-to-spike conversion using a graphene excitable laser

Abstract

Neuromorphic (brain-inspired) photonic systems process information encoded in the pulses of light, i.e., “spikes” that are analog in time but digital in amplitude. Applying these systems to process commonly used digital data requires a simple and effective interfacing solution to converting binary digits into spike sequence in the optical domain. Laser systems offer a variety of useful nonlinear functionalities, including excitable dynamics that can be found in the time-resolved “spiking” of neurons. We propose and demonstrate, both numerically and experimentally, an all-optical digital-to-spike (DTS) conversion scheme using a single graphene excitable laser (GEL) without clock signal synchronization. We first study the DTS conversion mechanism based on the simulation platform of an integrated GEL, which achieve a DTS conversion rate up to 10 Gbps. Our DTS conversion scheme can be operated under flexible input power conditions and exhibits a strong logic-level restoration capability. We then verify the feasibility of our approach via a proof-of-principle experiment where a fiber-based GEL obtains a DTS conversion rate of 40 Kbps, and a bit error rate (BER) of 10−9 with an input power of −24 dBm. This technology can be potentially applied in future neuromorphic photonic systems for information processing and computing.