title: Calculation of the torque on dielectric elliptical cylinders.
abstract: We present our investigation of the torque exerted on dielectric elliptical cylinders by highly focused laser beams. The calculations are performed with rigorous diffraction theory, and the size-dependent torque is analyzed as a function of the axis ratio. It is found that highly elongated particles will experience a reversal of the torque for a radius that is approximately one third of the wavelength. This effect is attributed to interference effects inside the structure due to multiple reflections of the incoming wave. The evolution from a perfectly sinusoidal angular dependence of the torque to a more complicated pattern for increasing particle size is presented in detail.
authors.affiliation: University of Neuchâtel, Institute of Microtechnology, CH-2000 Neuchâtel, Switzerland. carsten.rockstuhl@unine.ch
authors.forename: Carsten
authors.initials: C
authors.lastname: Rockstuhl
authors.forename: Hans Peter
authors.initials: HP
authors.lastname: Herzig