Physical Implementation of Optical Material-Based Neural Networks Processing Enabled by Long-Persistent Luminescence

Rapid advancements in artificial intelligence have magnified the inherent bottlenecks and energy inefficiencies of conventional von Neumann architecture. To address these limitations, processing information in a highly parallel, memory-integrated manner mimicking the human brain, neuromorphic devices have emerged as a cornerstone of next-generation computing. Among these, optical-neuromorphic devices are particularly promising. By using light, they offer transformative advantages, such as high speed, massive bandwidth, and minimal signal interference. Accordingly, we propose long-persistent luminescence (LPL) materials as novel substrates for optically operative artificial synapses. We utilize AGa₂O₄ (A = Mg, Ca, Sr, or Ba) luminescent oxides in which the intrinsic defect states enable excellent LPL properties without complex material engineering. Leveraging these properties, we demonstrate the physical implementation of optical material-based neural processing, in which memory retention and nonlinear transformation are executed within the LPL material. As proof of concept, this physical neural network was applied to a real-time Pong gameplay, demonstrating autonomous decision-making through light-driven signal processing. To further extend, we developed physical reservoir computing and physical neural network architectures. These architectures exploit the nonlinear temporal dynamics and luminescence mapping of LPL to perform handwritten digit recognition. Our findings establish LPL materials as a versatile platform for developing next-generation, energy-efficient optical-neuromorphic systems.