Photonic reservoir computing based on nonlinear wave dynamics at a microscale

High-dimensional nonlinear dynamical systems including neural networks can be utilized as a computational resource for information processing. In this sense, nonlinear wave systems are good candidate for such a computational resource. Here, we propose and numerically demonstrate information processing based on nonlinear wave dynamics in microcavity lasers, i.e., optical spatiotemporal systems at a microscale. One of the remarkable features is the ability of high-dimensional and nonlinear mapping of input information into the wave states, enabling efficient and fast information processing at a microscale. We show that the computational capability for nonlinear/memory tasks is maximized at the edge of the dynamical stability. Moreover, we also show that the computational capability can be enhanced by applying a time division multiplexing technique to the wave dynamics; thus, the computational potential of the wave dynamics can sufficiently be extracted even when the number of detectors to monitor the wave states is limited. In addition, we discuss the merging of optical information processing and optical sensing, opening a novel method of model-free sensing by using a microcavity reservoir itself as a sensing element. These results open a way to on-chip photonic computing with high-dimensional dynamics and a novel model-free sensing scheme.