A V-type all-optical switch based on third-order nonlinearity

All optical processing of data on an integrated photonic chip requires all-optical switches as a fundamental element to actively modulate the transmission of the signal light by the control light. Traditional all-optical switches as a function of the intensities of the input fields can be classified into three categories as the regular, the optical limiting and the bistable switches. In this work, a whispering gallery mode resonator coupled to a waveguide with third-order nonlinearity in the pump depletion regime is investigated. The transmission spectra of the signal light are able to be controlled by adjusting the power-dependent frequency shifts. We find that the frequency shifts of the cavity modes depend not only on the nonlinear processes of self- and cross-phase modulation but also on the coupling between the pump and the signal lights in the pump depletion regime. When the pump light is increased to milliwatts, the transmission coefficient of the nonresonant signal light has a critical point corresponding to the complete destructive interference from the combing effects of pump depletion, self- and cross-phase modulation. The results show that the output power of the signal light responds to the input power of the pump light with V-shaped curves. These input–output power curves can be utilized to construct a V-type all-optical switch for applications in automatic protection and monitoring the light intensity in optical communication network. Significantly, the V-type all-optical switch can also be constructed in system with both second- and third-order nonlinearities involved.