Sketch of the set-up considered: a droplet is illuminated by a Bessel beam such that the net force is a pull towards the laser source. A stress acts on the droplet setting in motion surface oscillations.
Polar plot of the angular distribution of force density σ plotted as , where . The shading indicates the value of . Comparison of pulling with order zero Bessel beam (net force towards the left) and conventional pushing by plane wave (net force towards the right). α = 11.35 in both cases.
Nondimensionalised optical force per cross-section area, Eq. (20), on front half and rear half of a water droplet during (a) conventional pushing by plane wave and (b) pushing/pulling by TM order zero Bessel beam. The middle graph in both panels shows the net force on the sphere. We let λ = 1.064 μm.
Droplet cross sections during optical pulling by a m = 0 Bessel beam, pulse duration 0.04 μs (solid line) and 0.02 μs (dashed line). The laser beam enters from the left. See main text for details.
Same as Fig. 4, but with shorter pulse duration (t 0 = 0.005 μs) and higher intensity ( W/μm2).
Surface oscillations irradiated by same power as in Fig. 4, but with a circularly polarized plane wave. Panel (a) shows approximately the maximum perturbation, panel (b) shows the relative elevation h(t)/a as a function of time at back (θ = 0) and front (θ = π) of droplet.
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