  Modern integrated circuits are essentially two-dimensional (2D). Partial
three-dimensional (3D) integration and 3D-transistor-level integrated circuits
have long been anticipated as routes to improve the performance, cost and size
of electronic computing systems. Even as electronics approach fundamental
limits however, stubborn challenges in 3D circuits, and innovations in planar
technology have delayed the dimensional transition. Optical computing offers
potential for new computing approaches, substantially greater performance and
would complement technologies in optical interconnects and data storage.
Nevertheless, despite some progress, few proposed optical transistors possess
essential features required for integration into real computing systems. Here
we demonstrate a logic gate based on universal features of nonlinear wave
propagation: spatiotemporal instability and collapse. It meets the scaling
criteria and enables a 3D, reconfigurable, globally-hyperconnected architecture
that may achieve an exponential speed up over conventional platforms. It
provides an attractive building block for future optical computers, where its
universality should facilitate flexible implementations.
