J. N. Wilking and T. G. Mason 2008 EPL 81 58005 doi:10.1209/0295-5075/81/58005
J. N. Wilking1 and T. G. Mason1,2,3
Show affiliationsCustom-shaped dielectric colloids in a simple focused laser beam create complex multi-dimensional potential landscapes. For laser powers above the threshold needed to trap spheres, many intricate shapes having holes and arms, as sampled using letters that have thicknesses comparable to the wavelength, can be trapped stably in more than one position and orientation. Particular trapped states can be reproducibly obtained by controlling how a particle enters the trap. By systematically enlarging the central hole of a square toroid, we alter the location, orientation, and existence of a trapped state. Thermal fluctuations of the trapped letter "N" cause Kramers hopping between two preferred orientational states, yielding a double-well angular potential.
05.40.-a Fluctuation phenomena, random processes, noise, and Brownian motion
Soft matter, liquids and polymers
Instrumentation and measurement
Issue 5 (March 2008)
Received 7 October 2007, accepted for publication 16 January 2008
Published 19 February 2008
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