| 1. |
- Odebo Länk, Nils, 1988, et al.
(author)
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Directional scattering and multipolar contributions to optical forces on silicon nanoparticles in focused laser beams
- 2018
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In: Optics Express. - : Optical Society of America. - 1094-4087 .- 1094-4087. ; 26:22, s. 29074-29085
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Journal article (peer-reviewed)abstract
- Nanoparticles made of high index dielectric materials have seen a surge of interest and have been proposed for various applications, such as metalenses, light harvesting and directional scattering. With the advent of fabrication techniques enabling colloidal suspensions, the prospects of optical manipulation of such nanoparticles becomes paramount. High index nanoparticles support electric and magnetic multipolar responses in the visible regime and interference between such modes can give rise to highly directional scattering, in particular a cancellation of back-scattered radiation at the first Kerker condition. Here we present a study of the optical forces on silicon nanoparticles in the visible and near infrared calculated using the transfer matrix method. The zero-backscattering Kerker condition is investigated as an avenue to reduce radiation pressure in an optical trap. We find that while asymmetric scattering does reduce the radiation pressure, the main determining factor of trap stability is the increased particle response near the geometric resonances. The trap stability for non-spherical silicon nanoparticles is also investigated and we find that ellipsoidal deformation of spheres enables trapping of slightly larger particles.
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| 2. |
- Miljkovic, Vladimir, 1982, et al.
(author)
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Simulating light scattering from supported plasmonic nanowires
- 2012
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In: Optics Express. - : Optical Society of America. - 1094-4087 .- 1094-4087. ; 20:10, s. 10816-10826
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Journal article (peer-reviewed)abstract
- We present a method for calculating the differential scattering cross sections from nanostructures close to an interface separating two semi-infinitive dielectric media. The method combines a fast finite element software (Comsol multiphysics), used for calculations of the fields around and inside the structure, and the Green's functions method, which is used to find the far field distribution from the calculated total fields inside the nanostructure. We apply the method to calculations of scattering spectra from silver nanowires supported by an air-glass interface, a system that is of high current interest in relation to various nanophotonics applications. The results are analyzed in relation to analytical models and compared to experimentally measured spectra, to which we find a good agreement.
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| 3. |
- Lehmuskero, Anni, et al.
(author)
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Plasmonic particles set into fast orbital motion by an optical vortex beam
- 2014
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In: Optics express. - : The Optical Society. - 1094-4087. ; 22:4, s. 4349-4356
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Journal article (peer-reviewed)abstract
- We optically trap plasmonic gold particles in two dimensions and set them into circular motion around the optical axis using a helically phased vortex laser beam. The orbiting frequency of the particles reaches 86 Hz, which corresponds to a particle velocity of the order 1 mm per second, for an incident laser power of a few tens of milliwatts. The experimentally determined orbiting frequencies are found to be well in line with the notion that the beam carries an orbital angular momentum of ħl per photon.
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