All-optical switching in microresonators using the Kerr nonreciprocity

Photonic circuits are spreading as a viable alternative to conventional electronic circuits. Electro-optic modulators (EOMs) are currently used as switches in telecommunications thanks to their simplicity and speed, however they are driven electrically. Several approaches have been demonstrated to realise all-optical switches such as ring lasers in which the lasing direction is controlled by an input seed, however these devices still require additional electrical or optical pumping. An alternative approach is to exploit the change in resonant frequency of nonlinear resonators with the input power. This has been successfully demonstrated in semiconductor resonators, where the nonlinearity is provided by the carrier generation from two-photon absorption, and in dielectric resonators governed by the Kerr effect. However, this approach needs the input to be in a narrow range of power and detuning from the cavity resonance and is adversely affected by the cavity's thermal drift due to the high circulating powers.