An Ultra-Compact Low-Power All-Optical GST-Based Plasmonic Switch for Non-Volatile Neuromorphic Synapses based on Triangular Cavity

Miniaturization and performance enhancement of photonic devices remain key challenges in the advancement of optical information processing technologies and photonic neural networks. In this study, an inverted triangular resonator (ITR) based on a metal–insulator–metal (MIM) plasmonic architecture and phase-change material Ge2Sb2Te5 (GST) is introduced. By integrating a GST element with a volume of only 78,000 nm³ into the active region of the ITR, strong electromagnetic field confinement and optimized phase transition control are achieved. This design results in an unprecedentedly small footprint (0.031 μm²) and an outstanding optical contrast of 76% at the telecommunication wavelength of 1598 nm. The switching energy of this structure, estimated by numerical simulations, is about 7 pJ, placing it among the most energy-efficient photonic devices. The unique features of this structure—including the extremely small volume of active material, low energy consumption, high thermal stability, and excellent reliability—make it an ideal candidate for implementing tunable optical synapses in neuromorphic systems. Its fast nonlinear response and stable operation enable precise simulation of synaptic weighting and the implementation of learning algorithms in photonic architectures. These results demonstrate that the intelligent combination of plasmonic technology and phase-change materials in the ITR configuration can open new horizons in the design of ultra-compact, low-power photonic devices for next-generation neural networks and optical information processing.