A ring optical resonator and one or more input optical waveguides are arranged on a substrate, and are arranged and positioned to establish evanescent optical coupling between them. The ring optical resonator, the substrate, or both include one or more nonlinear optical materials. To detect an electromagnetic signal at frequency νEM incident on the resonator, an input optical signal at frequency νIN propagates along the waveguide and around the resonator. The incident electromagnetic signal and the input optical signal generate one or more sideband optical signals at corresponding optical sideband frequencies νSF=νIN+νEM or νDF=νIN−νEM. To generate an electromagnetic signal to propagate away from the resonator, input optical signals at frequencies νIN1 and νIN2 propagate along one or more waveguides and around the resonator and generate the electromagnetic signal incident at frequency νEM=|νIN1−νIN2|.