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Tuesday, May 17, 2016

Tuning the stiffness asymmetry of optical tweezers via polarization control

Jinmyoung So, Jai-Min Choi

We report an experimental demonstration of tailoring the landscape of the optical potential by using the polarization state of a trap laser beam as a tuning knob. Two groups of polystyrene spheres, i.e., 300 nm and 1 μm, are optically trapped individually to investigate the effect of the intrinsic and a strongly-modified optical field distribution on the resulting trap stiffness, respectively. The angular variations of the orthogonal pair of stiffnesses, k x and k y , with the polarization state of the trap laser beam were systematically analyzed, and the results show that polarization control could provide a wide tuning range of trap-stiffness asymmetry (s T = 1− k x /k y ). The implication of asymmetry control of the optical potential is briefly discussed.

DOI

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