Displacement and localisation of a transparent nanosphere by light-pressure forces in the field of a focused laser beam

A.A. Afanas'ev and D.V. Novitsky

We report the results of a numerical simulation of the Langevin equation describing the motion of a transparent nanosphere under the action of a resulting light-pressure force in the field of a continuous focused Gaussian laser beam. The conditions for the localisation of the nanosphere near the focal waist of the beam focused by the lens are determined. An analytical solution of the approximate (truncated) equation of motion is found, which almost exactly coincides with the results of the numerical simulation of the initial equation.

DOI

On radiation forces acting on a transparent nanoparticle in the field of a focused laser beam

A A Afanas'ev, L S Gaida, D V Guzatov, A N Rubinov and A Ch Svistun

Radiation forces acting on a transparent spherical nanoparticle in the field of a focused Gaussian laser beam are studied theoretically in the Rayleigh scattering regime. Expressions are derived for the scattering force and Cartesian components of the gradient force. The resultant force acting on a nanoparticle located in the centre of a laser beam is found. The parameters of the focused beam and optical properties of the nanoparticle for which the longitudinal component of the gradient force exceeds the scattering force are determined. Characteristics of the transverse gradient force are discussed.

DOI

Formation of contour optical traps using a four-channel liquid crystal focusing device

A V Korobtsov, S P Kotova, N N Losevsky, A M Mayorova and S A Samagin
The capabilities and specific features of the formation and dynamic control of so-called contour optical traps using a fourchannel liquid crystal modulator are studied theoretically and experimentally. Circular, elliptical and C-shaped traps are formed. Trapping and confinement of absorbing micro-objects by the formed traps are demonstrated.

DOI

Measurement of interaction forces between red blood cells in aggregates by optical tweezers

A Yu Maklygin, A V Priezzhev, A Karmenian, Sergei Yu Nikitin, I S Obolenskii, Andrei E Lugovtsov and Kisun Li

We have fabricated double-beam optical tweezers and demonstrated the possibility of their use for measuring the interaction forces between red blood cells (erythrocytes). It has been established experimentally that prolonged trapping of red blood cells in a tightly focused laser beam does not cause any visible changes in their shape or size. We have measured the interaction between red blood cells in the aggregate, deformed by optical tweezers.

DOI

Optical forces in plasmonic nanoantennas

A S Shalin and S V Sukhov

The optical forces acting on nanoparticles in V-shaped plasmonic resonators with a high local-field gain have been investigated. Two versions are considered, which make it possible to implement either attractive or repulsive gradient optical forces. A plasmonic resonator is proposed, which can focus 350-nm radiation and implement a repulsive gradient force. It has been shown for the first time that a perturbation induced by a nanoparticle redistributes the field in the resonator so that additional intensity peaks arise in both versions to hold the nanoparticle in the resonator by forming an optical trap.

DOI

Chiral particles in a circularly polarised light field: new effects and applications

D V Guzatov and Vasilii V Klimov

Cross sections of scattering, absorption, and light pressure for a chiral spherical particle in a circularly polarised light field are studied for different values of the radius, dielectric constant, permeability, and parameter of the chiral particle. The conditions are found under which the cross sections of absorption and light pressure differ significantly when nanoparticles are exposed to light with different polarisations, which can be used to improve synthesis of chiral nanoparticles of complex structure.

DOI

Optical manipulators of microparticles using femtosecond laser radiation

V V Buchanov, V A Derzhavin, A D Zalesskii, I V Reshetov, Oleg M Sarkisov and A I Shushin

Two setups for manipulating (translocation, stretching, rotation) microscopic objects (with the dimensions from several nanometers to tens of micrometers) are developed based on optical trapping by femtosecond laser radiation. The possibility of single-cell translocation is shown. The possibility of destructing malignant cells as well as of cutting off a fragment from a malignant cell cluster due to the rapture of bonds is demonstrated in multiphoton absorption of femtosecond light pulses. The possibility of the holographic control to move several particles simultaneously is shown.

DOI