ph5b00605_si_001.pdf (1.19 MB)
Exploiting Optical Asymmetry for Controlled Guiding of Particles with Light
journal contribution
posted on 2016-02-10, 15:02 authored by Ognjen Ilic, Ido Kaminer, Yoav Lahini, Hrvoje Buljan, Marin SoljačićConventional methods of manipulating
particles with light, such
as optical tweezers and optical tractor beams, rely on beam-shaping
to realize complex electromagnetic field profiles and are thus sensitive
to scattering. Here, we show that, by introducing tailored optical
asymmetry in the particle, we can realize a novel guiding method that
is controllable by the frequency of light, without regard to the direction
or the shape of the light beam. With detailed stochastic simulations,
we demonstrate guiding of a two-faced nanoparticle where the optically
induced thermophoretic drift serves as the propulsion mechanism. Exploiting
the difference in resonant absorption spectra of the two materials,
we create a bidirectional local thermal gradient that is externally
switchable. This is advantageous because the frequency of a light
beam, unlike its shape or coherence, is preserved even in strongly
scattering environments. Since this approach is insensitive to scattering
and applicable to many particles at once, as well as particles that
cannot be optically resolved, it may enable useful applications in
biology, microfluidics, in vivo tasks, and colloidal science.