Macroscopic direct observation of optical spin-dependent lateral forces and left-handed torques

Abstract

Observing and taming unusual effects arising from non-trivial light-matter interaction has always triggered scientists to better understand Nature and develop technological tools towards implementing novel applications. Recently, several unusual optomechanical effects have been unveiled when subtle spin-orbit interactions come at play to build up optical forces and torques that are hardly seen in everyday life, such as negative optical radiation pressure, transverse optical forces, or left-handed optical torques. To date, there are only a few experimental proposals to reveal these effects despite tremendous conceptual advances. In particular, spin-dependent lateral forces and their angular analog are done either at the expense of direct observations or at the cost of specific instrumental complexity. Here we report on naked-eye identification of light-induced spin-dependent lateral displacements of centimeter-sized objects endowed with structured birefringence. Its angular counterpart is also discussed and the observation of left-handed macroscopic rotational motion is reported. The unveiled effects are ultimately driven by lateral optical force fields that are five orders of magnitude larger than those reported so far. These results allow structured light-matter interaction to move from a scientific curiosity to a new asset for the existing multidisciplinary optical manipulation toolbox across length scales. In addition, this highlights the spin-orbit optomechanics of anisotropic and inhomogeneous media, which is just beginning to be explored.

References in corpus (12)

• Spin-orbit interactions of light
• Optical spin-to-orbital angular momentum conversion in inhomogeneous anisotropic media
• Extraordinary momentum and spin in evanescent waves
• Lateral Optical Force On Chiral Particles Near a Surface
• Direct measurements of the extraordinary optical momentum and transverse spin-dependent force using a nano-cantilever
• Dynamic Consequences of Optical Spin-Orbit Interaction
• Transverse Chiral Optical Forces by Chiral Surface Plasmon Polaritons
• The optical torque on small bi-isotropic particles
• Transverse spinning of a sphere in a plasmonic field
• Directional spontaneous emission and lateral Casimir-Polder force on an atom close to a nanofiber
• Plasmonic lateral forces on chiral spheres
• Optical "Bernoulli" forces

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• Giant Lateral Optical Forces on Rayleigh Particles near Hyperbolic and Extremely Anisotropic Metasurfaces
• Lateral Optical Forces on Linearly-Polarized Emitters near a Reciprocal Substrate
• Subfemtonewton force fields measured with ergodic Brownian ensembles
• Radiation forces and torques in optics and acoustics
• Spin-governed topological surfaces and broken spin-momentum locking in a gyromagnetic medium
• Precise in situ radius measurement of individual optically trapped microspheres using negative optical torque exerted by focused vortex beams
• Microscopic Metavehicles Powered and Steered by Embedded Optical Metasurfaces
• Detection of radiation torque exerted on an alkali-metal vapor cell
• Optical Propulsion and Levitation of Metajets