We prove an optical radiation Earnshaw theorem: A small dielectric particle cannot be trapped by using only the scattering force of optical radiation pressure. A corollary is that the gradient or dipole force is necessary to any successful optical trap. We discuss the implications of the theorem for recent proposals for the optical trapping of neutral atoms.
© 1983 Optical Society of America
Original Manuscript: June 6, 1983
Published: October 1, 1983
A. Ashkin and J. P. Gordon, "Stability of radiation-pressure particle traps: an optical Earnshaw theorem," Opt. Lett. 8, 511-513 (1983)