Résumé
Nonlinearity induced by intensity-dependent refractive indices (Kerr media) can be used as a means to conceive light detectors sensitive to very weak excitation. This property results from the bistability properties of the nonlinear SchrÄodinger equation submitted to boundary value data on the finite interval. The detector is obtained by coupling two single 1D waveguide to a 2D slab waveguide with adjusted indices. The resulting device then presents unusual light propagation properties and in particular may switch from almost vanishing to intense output under excitation by a weak signal.