Thursday, 20 December 2012

Paper published in Optics Letters

Our paper 'Trapping volume control in optical tweezers using cylindrical vector beams' has been published as S. E. Skelton et al, Optics Letters 30 28-30 (2013).

From the abstract: We present the result of an investigation into the optical trapping of spherical microparticles using laser beams with a spatially inhomogeneous polarization direction [cylindrical vector beams (CVBs)]. We perform three-dimensional tracking of the Brownian fluctuations in the position of a trapped particle and extract the trap spring constants. We characterize the trap geometry by the aspect ratio of spring constants in the directions transverse and parallel to the beam propagation direction and evaluate this figure of merit as a function of polarization angle. We show that the additional degree of freedom present in CVBs allows us to control the optical trap strength and geometry by adjusting only the polarization of the trapping beam. Experimental results are compared with a theoretical model of optical trapping using CVBs derived from electromagnetic scattering theory in the T-matrix framework.

Monday, 17 December 2012

PhD Studentships Available

Two PhD studentships are available to work on a project funded by the Leverhulme Trust titled 'Exploring stochastic thermodynamics with optical traps', starting in 2013. The aim of this project is to use optical trapping experiments as a test-bed for fluctuation relations in non-equilibrium (driven) systems.

Project abstract: The theory of equilibrium statistical mechanics is well established, and has found direct or indirect confirmation in a wide range of experiments. This is not the case for the emerging field of non-equilibrium statistical mechanics. In this case, a general theory has yet to be formulated, although a number of theorems (e.g. fluctuation and work theorems) have been introduced to link different physical quantities in systems out of equilibrium. The aim of the proposed research is to develop further, through proof-of-principle experiments with optical traps, the foundations of non-equilibrium statistical mechanics, with a view towards a unified description. 

Studentships will pay a stipend and fees at the rate applicable for UK and European Union students only.

Contact Dr Phil Jones for further details