Coherent-feedback control strategy to suppress spontaneous switching in ultra-low power optical bistability

Abstract: An optical resonator with intracavity Kerr nonlinearity can exhibit dispersive bistability suitable for all-optical switching. With nanophotonic elements it may be possible to achieve attojoule switching energies, which would be very attractive for ultra-low power operation but potentially problematic because of quantum fluctuation-induced spontaneous switching. In this manuscript I derive a quantum-optical model of two Kerr-nonlinear ring resonators connected in a coherent feedback loop, and show via numerical simulation that a properly designed controller' cavity can significantly reduce the spontaneous switching rate of a bistableplant' cavity in a completely embedded and autonomous manner.