Prof. Helen Gleeson: Pushing, pulling and twisting liquid crystals with laser tweezers

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      Pushing, pulling and twisting liquid crystals with laser tweezers

      Prof. Helen Gleeson, School of Physics and Astronomy, University of Manchester, UK

 

Laser tweezers are a beautiful tool to use with liquid crystal systems because the forces they exert (picoNewtons) are of the same order as those associated with deformations in liquid crystals.  While laser tweezers have been used to probe defects in liquid crystals and to create beautiful colloidal structures, this talk focuses on two dynamic applications. In the first, laser tweezers are used to measure local viscosity coefficients in liquid crystals. They are a unique tool to do so as they allow us to work in the low Ericksen regime. In the second application, we demonstrate how liquid crystalline droplets can be rotated in laser tweezers, forming all-optical switches.  Finally we show a unique system where linearly polarized lasers can induce a continuous rotation of some special liquid crystal droplets.