Abstract
Abstract
We show that if a dielectric nanoparticle (with a diameter of ∼70 nm) is placed on the optical axis near the surface (at a distance of less than 100 nm) of a high-aperture silicon gradient microlens with a refractive index in the form of a hyperbolic secant, and the lens is illuminated by laser radiation with a wavelength of 1.55 μm, then the particle is attracted to the lens surface with a force of a fraction of a piconewton. If there is a nanohole in the lens output surface, then the nanoparticle is pulled into it. This represents a kind of an ‘optical magnet.’ If a reverse energy flow is formed on the optical axis near the output surface of a gradient lens, then its presence leads to the fact that a dielectric nanoparticle with absorption will be ‘attracted’ to the surface with a greater force than a similar particle without absorption. In the absence of a reverse flow, both particles (with and without absorption) are attracted equally. We show also that in the nanohole, where the reverse energy flux is maximum, the light is right-hand circularly polarized, although the lens is illuminated by a left-hand circularly polarized light. The fields are calculated using the finite difference method in the time domain and the forces are calculated using the Maxwell stress tensor.
Funder
Russian Science Foundation
Russian Foundation for Basic Research
RF Ministry of Science and Higher Education
Subject
Atomic and Molecular Physics, and Optics,Electronic, Optical and Magnetic Materials
Cited by
3 articles.
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