All-Optical Switching in an Add-Drop Resonator using Two-Photon Absorption in Warm Rubidium Vapor

The need for low-power optical switching in the fields of quantum information and classical logic has been well documented. Here we present results showing all-optical switching using a Si$_3$N$_4$ micro-disk cavity, in an add/drop configuration, evanescently coupled to hot Rubidium (Rb) vapor. The atomic vapor only dissipates the energy in the cavity when control and signal frequencies sum to a Rb two-photon S-P-D transition. This suppresses the cavity build-up and alters the output path of the signal light. Devices of this type can exhibit fast switching times with ultra-low energy dissipation which make them viable technologies for application in classical logic or quantum information processing.