Forces on a Rayleigh particle in the cover region of a planar waveguide

Abstract

Abstract-We report on the optimization of a waveguide structure for the maximization of the radiation forces exerted on a Rayleigh particle in the cover region. The two main radiation forces involved are the transverse gradient force which attracts a particle into the waveguide and the combined scattering and dissipative forces which drive the particle forward along the channel. The dependence of these forces on parameters including the incident wavelength, the surrounding medium embedding the particles, and the polarizability of the particles is discussed. Both dielectric and metallic gold spheres of radius 10 nm are considered in the model. Special emphasis is devoted to the maximization of the transverse gradient force due to the optical intensity gradient at the waveguide surface, and the wavelength dependence of the polarizability of gold nanoparticles.

Near-Field Light Scattering Techniques for Measuring Nanoparticle-Surface Interaction Energies and Forces

“…8 can be generalized for both metallic and dielectric Rayleigh particles [41]. Theory and experiments have confirmed these models for free-space optical tweezers [55-57], and the applicability of these models to near-field interactions has also been extensively established through theory [58] and simulations [52]. For larger particles where the Rayleigh approximation does not hold, the magnitude of the scattered light will not increase monotonically with size owing to morphology dependent resonances.…”

Optical micromanipulations in the non‐diffractive regime

“…In the multimode waveguide, each mode could be generated by changing the position of the coupling objective, and the velocity of the driven particles have been found to decrease with higher order modes, which could be attributed to the reduced field density at the centre of the wave guide. Recently waveguide based near field manipulation of particles has been demonstrated, where the evanescent waves confine the particles to the surface of the waveguide and the scattering and absorption forces aid in propelling them [19,20]. Such waveguide based optical transport of dielectric particles [16,21], metallic particles [22,23] and cells [24] have been achieved.…”

Optical Effects Induced by Bloch Surface Waves in One-Dimensional Photonic Crystals

“…However, an electromagnetic gradient can be created not only in the waist region of focused laser radiation. The possibility of trapping and moving nanoparticles and microparticles using an evanescent field that appeared with total internal reflection from a smooth surface and in optical waveguides was shown [64][65][66][67]. Large values of optical field gradients can be achieved by using optical resonances of surface plasmons on metallic films and in plasmonic structures [68][69][70][71][72][73].…”