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Physical Review Letters

Observation of Radiation-Pressure Trapping of Particles by Alternating Light Beams

Arthur Ashkin, J. M. Dziedzic

Published Mar 25, 1985• 115 citations
Publisher

Abstract

The new principle of radiation-pressure trapping of neutral dielectric particles by means of alternating light beams was demonstrated in an optical levitation experiment. Stable trapping of micron-sized spheres was observed due to alternating scattering-force fields under conditions where stable cw trapping was not possible. Application of this principle to neutral-atom trapping as a means of circumvention of the optical Earnshaw theorem is suggested. A new stable cw optical trap for spheres was also discovered.

DOI
10.1103/physrevlett.54.1245

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The new principle of radiation-pressure trapping of neutral dielectric particles by means of alternating light beams was demonstrated in an optical levitation experiment. Stable trapping of micron-sized spheres was observed due to alternating scattering-force fields under conditions where stable cw trapping was not possible. Application of this principle to neutral-atom trapping as a means of circumvention of the optical Earnshaw theorem is suggested. A new stable cw optical trap for spheres was also discovered.
Radiation pressure forces have been proposed for making stable optical traps for neutral atoms and other dielectric particles. Recently introduced optodynamic or alternating beam traps based on the scattering force are compared with cw traps based on the gradient force. Trapping experiments on micron-sized dielectric particles are described which demonstrate the basic principles of alternating beam light trapping. The relationship of these traps to the optical Earnshaw theorem is considered. The implications for trapping of recently demonstrated sources of slow atoms are also discussed.