Optical forces acting on a particle near photonic crystal surface

We consider optical forces acting on resonant particles located near the surface of a photonic crystal (PC). The band structure of the PC makes it possible to change the direction of propagation of the BSW (Bloch surface wave) to the opposite when varying the wavelength of the incident radiation, which leads to a change in the direction of the reactive optical force component. Therefore, there is an effect of switching between the modes of optical attraction and repulsion of particles in narrow spectral ranges, which is prospective for precise sorting of resonant particles. Here we consider sorting of core-shell dielectric-gold nanoparticles with varying shell thickness.