Abstract
AbstractThe ability to manipulate small objects with focused laser beams has opened a venue for investigating dynamical phenomena relevant to both fundamental and applied sciences. However, manipulating nano‐sized objects requires subwavelength field localization, provided by auxiliary nano‐ and microstructures. Particularly, dielectric microparticles can be used to confine light to an intense beam with a subwavelength waist, called a photonic nanojet (PNJ), which can provide sufficient field gradients for trapping nano‐objects. Herein, the scheme for wavelength‐tunable and nanoscale‐precise optical trapping is elaborated, and the possibility of lateral nanoparticle movement using the PNJ's side lobes is shown for the first time. In addition, the possibility of subwavelength positioning using polarization switching is shown. The estimated stability with respect to Brownian motion is higher compared to conventional optical trapping schemes.
Highlights
Additional degrees of freedom for optical manipulation could be provided by dielectric microparticles and nanojet (PNJ), which can provide sufficient field gradients for trapping their ensembles, generating photonic nano-objects
PNJs can trap any nanoparticle, including metallic ones, in spite of repulsive scattering forces
In this Letter, we theoretically study optical forces in tunable PNJs generated by microspheres and microellipsoids
Summary
The ability to manipulate small objects with focused laser beams has opened concept for improving optical tweezers is a venue for investigating dynamical phenomena relevant to both fundamental to employ auxiliary plasmonic and dielecand applied sciences. Additional degrees of freedom for optical manipulation could be provided by dielectric microparticles and nanojet (PNJ), which can provide sufficient field gradients for trapping their ensembles, generating photonic nano-objects. Notice that the direction of the gradient force (Figure 2) is invariant with respect to the size and refractive index of the nanoparticle if these parameters are in the range of the dipole approximation applicability (Equations (1) and (2)) and so the length of the arrows is given in arbitrary units. Plane wave propagates along the main z-axis, the two linear polarizations (x- and y-polarizations) result in apparently different
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