Ultrafast Spinning of Gold Nanoparticles in Water Using Circularly Polarized Light
Journal article, 2013

Controlling the position and movement of small objects with light is an appealing way to manipulate delicate samples, such as living cells or nanoparticles. It is well-known that optical gradient and radiation pressure forces caused by a focused laser beam enables trapping and manipulation of objects with strength that is dependent on the particles optical properties. Furthermore, by utilizing transfer of photon spin angular momentum, it is also possible to set objects into rotational motion simply by targeting them with a beam of circularly polarized light. Here we show that this effect can set similar to 200 nm radii gold particles trapped in water in 2D by a laser tweezers into rotation at frequencies that reach several kilohertz, much higher than any previously reported light driven rotation of a microscopic object. We derive a theory for the fluctuations in light scattering from a rotating particle, and we argue that the high rotation frequencies observed experimentally is the combined result of favorable optical particle properties and a low local viscosity due to substantial heating of the particles surface layer. The high rotation speed suggests possible applications in nanofluidics, optical sensing, and microtooling of soft matter.

spin angular momentum

optical torque

photothermal effects

Optical tweezers



Anni Lehmuskero

Chalmers, Applied Physics, Bionanophotonics

Robin Ogier

Chalmers, Applied Physics, Bionanophotonics

Tina Gschneidtner

Chalmers, Chemical and Biological Engineering, Polymer Technology

Peter Johansson

Chalmers, Applied Physics, Bionanophotonics

Mikael Käll

Chalmers, Applied Physics, Bionanophotonics

Nano Letters

1530-6984 (ISSN) 1530-6992 (eISSN)

Vol. 13 7 3129-3134

Subject Categories

Chemical Sciences

Condensed Matter Physics



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