[8p-C212-1~16] 3.1 Basic optics and frontier of optics

5:30 PM - 5:45 PM JST(8:30 AM - 8:45 AM UTC)

[8p-C212-13] Spin or Orbital Origin of Optical Torque in Gold Nanostructures

〇Shun Hashiyada^1,2, Yoshito Tanaka¹ (1.RIES, Hokkaido Univ., 2.JST-PRESTO)

Keywords:

optical torque,optical spin angular momentum,optical orbital angular momentum

We analyze the spin and orbital origins of optical torque in gold nanostructures based on angular momentum transfer to matter. By directly evaluating the material spin angular momentum transfer and deriving the orbital contribution, we distinguish whether the optical torque originates from spin angular momentum (SAM) or orbital angular momentum (OAM). For a gold nanosphere under circularly polarized light, the angular momentum transfer is dominated by SAM. In contrast, for a gold nanorod, both circularly polarized light and linearly polarized light tilted by 45° from the long axis produce optical torque dominated by OAM transfer.