The theory of heterogeneous dielectric nanostructures with non-typical low-threshold nonlinearity

The recently discovered, ultralow-threshold, nonlinear refraction of low-intensity laser radiation in dielectric nanostructures has an atypical dependence on radiation intensity in the pulsed and continuous modes. In this study, we present a theoretical explanation. The theory suggests that the nonlinearity is photoinduced in nature, rather than thermal, and depends directly on the nanoparticle electronic structure and the relationship between permittivities of the dielectric matrix and the nanoparticles.