Controlling Lateral Fano Interference Optical Force with Au–Ge₂Sb₂Te₅ Hybrid Nanostructure

We numerically demonstrate that a pronounced dipole–quadrupole (DQ) Fano resonance (FR) induced lateral force can be exerted on a dielectric particle 80 nm in radius ( R sphere = 80 nm) that is placed 5 nm above an asymmetric bow-tie nanoantenna array based on Au/Ge 2 Sb 2 Te 5 dual layers. The DQ-FR-induced lateral force achieves a broad tuning range in the mid-infrared region by changing the states of the Ge 2 Sb 2 Te 5 dielectric layer between amorphous and crystalline and in turn pushes the nanoparticle sideways in the opposite direction for a given wavelength. The mechanism of lateral force reversal is revealed through optical singularity in the Poynting vector. A thermal–electric simulation is adopted to investigate the temporal change of the Ge 2 Sb 2 Te 5 film’s temperature, which demonstrates the possibility of transiting the Ge 2 Sb 2 Te 5 state by electrical heating. Our mechanism by tailoring the DQ-FR-induced lateral force presents clear advantages over the conventional nanoparticle manipulation techniques: it possesses a pronounced sideways force under a low incident light intensity of 10 mW/μm 2, a fast switching time of 2.6 μs, and a large tunable wavelength range. It results in a better freedom in flexible nanomechanical control and may provide a new means of biomedical sensing and nano-optical conveyor belts.