Light storage in a wavy dielectric grating with Kerr nonlinearity

Periodical corrugation in the dielectric slab transforms the two waveguide modes at zero Bloch wave number into a leaky resonant mode and symmetry-protected bound states in the continuum (BIC) with a small frequency detuning. The leaky resonant mode can be directly excited by a weakly linearly polarized normally incident optical field. In the presence of Kerr nonlinearity, BIC can be indirectly excited by an optically bistable response. Two types of bistable operations were considered. For the first type, the intensity of the incident field was gradually increased to exceed the critical value and then decreased to zero. For the second type, the intensity was fixed, while the linear polarization angle of the incident field was gradually increased to exceed a critical value and then decreased to ${0}^{\ensuremath{\circ}}$. Theoretically, the indirectly excited BIC can store optical energy without loss, even when the intensity of the incident field decreases to zero. The incidence of an optical field with double frequency or orthogonal linear polarization can erase the stored optical field by destroying BIC. The proposed system can function as an optical storage and switching device.