[18p-A201-1~11] 3.1 Basic optics and frontier of optics (merged with formerly 3.2 Equipment optics and materials)

▲ [18p-A201-7] Right- and left-handed optical torques acting on vanadium oxide particles

〇Pin Christophe¹, Keiji Sasaki¹ (1.RIES, Hokkaido Univ.)

Keywords:optical torque, vanadium dioxide, nonlinear optical force

Because of the fast insulator-to-metal phase transition of VO₂, VO₂ nanoparticles in water solution are optically trapped in orbit around a focused IR laser beam. For particles large enough that are optically trapped using a circularly polarized Gaussian beam, spin-to-orbital angular momentum conversion results in the light spin-induced orbital rotation of the trapped particle, which enables controlling the rotation direction of the trapped particle. In this work, we conduct a more detailed investigation of the optical torque acting on trapped VO₂ particles. First, we demonstrate that the phase transition causes a flip of the optical torque handedness for a given range of particle sizes. Second, we show that particles with different size, shape and/or material composition may experience optical torques with opposite handedness. We study how the heterogeneous material composition of vanadium oxide particles and clusters influences the handedness of the optical torque.