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Transverse optical gradient force in untethered rotating metaspinners

Authors :
Engay, Einstom
Shanei, Mahdi
Mylnikov, Vasilii
Wang, Gan
Johansson, Peter
Volpe, Giovanni
Käll, Mikael
Publication Year :
2024

Abstract

We introduce optical metasurfaces as components of ultracompact untethered microscopic metaspinners capable of efficient light-induced rotation in a liquid environment. Illuminated by weakly focused light, a metaspinner generates torque via photon recoil through the metasurfaces' ability to bend light towards high angles despite their sub-wavelength thickness, thereby creating orbital angular momentum. We find that a metaspinner is subject to an anomalous transverse optical gradient force that acts in concert with the classical gradient force. Consequently, when two or more metaspinners are trapped together in a laser beam, they collectively orbit the optical axis in the opposite direction to their spinning motion, in stark contrast to rotors coupled through hydrodynamic or mechanical interactions. The metaspinners delineated herein not only serve to illustrate the vast possibilities of utilizing optical metasurfaces for fundamental exploration of optical torques, but they also represent potential building-blocks of artificial active matter systems, light-driven micromachinery, and general-purpose optomechanical devices.

Subjects

Subjects :
Physics - Optics

Details

Database :
arXiv
Publication Type :
Report
Accession number :
edsarx.2406.11489
Document Type :
Working Paper