38 research outputs found
Radiation induced force between two planar waveguides
We study the electromagnetic force exerted on a pair of parallel slab
waveguides by the light propagating through them. We have calculated the
dependence of the force on the slab separation by means of the Maxwell--Stress
tensor formalism and we have discussed its main features for the different
propagation modes: spatially symmetric (antisymmetric) modes give rise to an
attractive (repulsive) interaction. We have derived the asymptotic behaviors of
the force at small and large separation and we have quantitatively estimated
the mechanical deflection induced on a realistic air-bridge structure.Comment: 10 pages, 6 figure
Strong optical force induced by morphology dependent resonances
We consider the resonant optical force acting on a pair of transparent
microspheres by the excitation of the Morphology Dependent Resonance (MDR). The
bonding and anti-bonding modes of the MDR correspond to strong attractions and
repulsions respectively. The dependence of the force on separation and the role
of absorption are discussed. At resonance, the force can be enhanced by orders
of magnitude so that it will dominate over other relevant forces. We find that
a stable binding configuration can be induced by the resonant optical force.Comment: 4 pages, 4 figure
Localized vibrational modes in optically bound structures
We show, through analytical theory and rigorous numerical calculations, that
optical binding can organize a collection of particles into stable
one-dimensional lattice. This lattice, as well as other optically-bound
structures, are shown to exhibit spatially localized vibrational eigenmodes.
The origin of localization here is distinct from the usual mechanisms such as
disorder, defect, or nonlinearity, but is a consequence of the long-ranged
nature of optical binding. For an array of particles trapped by an interference
pattern, the stable configuration is often dictated by the external light
source, but our calculation revealed that inter-particle optical binding forces
can have a profound influence on the dynamics.Comment: 4 pages, Optical Bindin
Optical binding of particles with or without the presence of a flat dielectric surface
Optical fields can induce forces between microscopic objects, thus giving
rise to new structures of matter. We study theoretically these optical forces
between two spheres, either isolated in water, or in presence of a flat
dielectric surface. We observe different behavior in the binding force between
particles at large and at small distances (in comparison with the wavelength)
from each other. This is due to the great contribution of evanescent waves at
short distances. We analyze how the optical binding depends of the size of the
particles, the material composing them, the wavelength and, above all, on the
polarization of the incident beam. We also show that depending on the
polarization, the force between small particles at small distances changes its
sign. Finally, the presence of a substrate surface is analyzed showing that it
only slightly changes the magnitudes of the forces, but not their qualitative
nature, except when one employs total internal reflection, case in which the
particles are induced to move together along the surface.Comment: 8 pages, 9 figures, and 1 tabl