Non-volatile programmable directional couplers for high-integration and low-loss photonic computing

The rapid growth of artificial intelligence creates a pressing need for high-speed, low-cost photonic computing technologies, which remain hindered by integration density, optical loss, and computational precision. Here, we demonstrate a non-volatile programmable directional coupler based on low-loss Sb 2 Se 3 phase-change material, featuring an insertion loss of 0.3 dB. The device achieved 197 distinct non-volatile optical states within a coupling length of only 28 μm. This high-precision control was enabled by a novel programming method leveraging a dual-band fiber array. Functioning as a matrix multiplication unit, this device facilitated the photonic neural network to attain an accuracy of 92.27% on the Fashion-MNIST dataset, paving the way for high-density, high-precision, and energy-efficient photonic computing.