Tunable Fano resonances and enhanced optical bistability in composites of coated cylinders due to nonlocality

Theoretical studies of the optical bistability in two-dimensional nonlinear composites, where Kerr type dielectric/nonlocal metal core-shell cylinders are randomly embedded in the host medium, have been carried out. Within the quasistatic approximation, we demonstrate the tunable Fano resonances in the scattering spectra of the single core-shell cylinder based on different degrees of nonlocality in the linear case. It is found that nonlocality of the metallic shell would enhance the Fano resonance peak and the near-field strength, thus it can further boost the nonlinear response of the core-shell cylinder in both near field and far field, indicating the nonlocality-enhanced optical bistability. Furthermore, we show that nonlocality can efficiently reduce the bistable switching threshold of the nonlinear composite, and these self-tunable optical resonant scatters can be used as all-optical switches and nanomemories.