Nonlinear Excitation and Self-Action of Bloch Surface Waves Governed by Gradient Optical Forces

Self-action of light is among the most important nonlinear optical effects with a plethora of present and potential applications. Suspensions of subwavelength particles are characterized by high artificial optical nonlinearity induced by gradient optical forces. Here, we report on an experimental study of self-action of the Bloch surface wave (BSW) excited at the interface between a one-dimensional photonic crystal and a water suspension of dielectric nanoparticles by a continuous-wave diode laser. We demonstrate the modification of the BSW resonance with increasing optical power and, for the first time to our knowledge, experimentally show self-focusing of BSWs. A plane-wave model is used to describe the mechanism of the observed resonance modification. Our results demonstrate the great potential of guided waves in multilayer structures for optical signal processing and open up new possibilities for the light-controlled operation of BSWs.