ИСТИНА

Bloch surface waves (BSW) are surface electromagnetic modes that propagate in all-dielectric structures and provide large local field enhancement. In our work, BSWs are shown to be a promising tool for optical manipulation of dielectric microparticles. Momentum of the BSW at a one-dimensional photonic crystal/water interface is experimentally demonstrated to be transferred to a 1-μm polystyrene microsphere located in the vicinity of the photonic crystal surface. As it is observed by means of optical microscopy, the interaction force generated by the BSW is large enough for particle localization near the surface and propulsion along the BSW propagating direction. To measure the force quantitatively, photonic force microscopy is used. Photonic force microscopy technique is based on the determination of the particle displacement in an optical tweezers trap at an external force influence. The measured force decays exponentially with moving off the surface at large distances, but there is a surprising diminution of the force at surface/particle gaps less than 150 nm. The maximum value of 0.25 fN at the exciting radiation intensity of 1.6 kW/cm^2 is observed at the BSW excitation resonance.