Manipulation of Islands on Freely Suspended Smectic Films and Bubbles Using Optical Tweezers

Noel Clark ,Apichart Pattanaporkratana ,Cheol S. Park ,Joseph E. Maclennan

Ferroelectric Liquid Crystal Materials Research Center, Department of Physics, University of Colorado, Boulder, CO 80309, USA

Smectic liquid crystals can be made to form freely suspended films and bubbles, locally quantized in thickness by an integral number N of smectic layers, on which islands, circular regions of greater thickness than the surrounding film area, can be generated. Here we demonstrate that such islands can be manipulated using optical tweezers. We have investigated experimentally and theoretically the optical trapping forces on islands with radii in the range 1 < R < 100 Ám and thickness N ~ 300 layers on background films and bubbles of Nf ~ 50 layers. With the trapping laser beam focused to a spot size small compared to the diameter of an island, the trapping force is found to be maximized when the edge of the island passes through the center of the beam, as predicted. The optical tweezer system will be used to study the static and dynamic interactions between islands.

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