Bistable Goos–Hänchen shift owing to leaky-mode excitation in a slab waveguide with Kerr nonlinear medium

We investigate the nonlinear Goos–Hänchen shift of a light beam reflected from a prism-coupled leaky waveguide containing a Kerr medium. As the incident power varies, the system can switch between two states, total internal reflection and frustrated total reflection, owing to the inherent positive feedback arising from the intensity-dependent guiding mode resonance. The reflectance exhibits optical bistability; meanwhile, the lateral shift of the reflected beam also shows hysteresis behavior. It is found that the transition between the two stable states is related to the excitation of a leaky mode in the waveguide, which results from the modulation of the electric field in the nonlinear substrate. We also analyze the effects of system parameters on the bistable Goos–Hänchen shift. The thresholds as well as the width of the hysteresis curve are sensitive to the thicknesses of the gap layer and the guiding layer, which determine the resonance angle. The bistable lateral displacement in the slab waveguide may have potential applications in optical switching, beam steering, etc.