Nanophotonic Approach to Energy-Efficient Ultra-Fast All-Optical Gates

All-optical processing is based on fast nonlinear effects, such that light can be used to control light. The development of a novel class of low-loss semiconductor optical resonators, capable of field confinement close to the diffraction limit, has decreased the power level required to trigger nonlinear effects by several orders of magnitude. We review a decade of research on all-optical gates aiming both at fast and energy-efficient operation, with the prospect of integration on a silicon photonics platform.