An Optical Scheme of On-Chip Matrixing by Phase-Change Based Tunable Weighting of Photonic Tensor Unit

In this paper, we propose an optical scheme of on-chip matrixing for matrix-vector multiplications (MVMs) by configuring each matrix element into a photonic tensor processing unit (TPU) with wavelength division multiplexing and the actively tunable weighting for scalar multiplication. The low loss chalcogenide phase change material of Ge2Sb2Se4Te (GSST) is employed and modeled with intermediate states for multilevel tunable weighting of each TPU. The dynamic electro-thermal process of GSST phase transition using ITO for electrical heating is simulated and well confirms the switchable weighting of TPUs. Simulation results reveal that a 7 V voltage pulse of 500 ns duration followed by a 9 V voltage pulse of 1500 ns duration and another pulse of 14 V voltage and 500 ns duration can set data value of '0' and '1' for each TPU. Taking a set of incident light with varied wavelengths and powers as input vectors, the quantized MVM outputs of photocurrents with varied amplitude are obtained after photoelectric conversion. Finally, the photonic integrated circuit level simulations by Lumerical INTERCONNECT perfectly confirm our scheme of on-chip matrixing for optical MVMs and computing.