Abstract
The discrete dipole approximation (DDA) is a well-known method for
computation of the scattering of light from nonspherical particles.
Here, we present a new scattering order formulation (SOF) of the DDA
that allows the user to represent the scattering particle with higher
flexibility than in conventional DDAs, while the computer memory
required always scales as O(N). In our new SOF, the user can locate
each dipole independently, or off-grid, in space, assign each dipole a
unique size and a unique dipole shape as appropriate, and assign each
dipole a unique magnetoelectric polarizability with no constraints.
The cost of this flexibility is that the computation time is increased
from O(NlogN) to O(N2). To compensate, our model allows the
user to vary the range of dipole interaction in a unique manner. We
find that, in cases in which the scatterer has at least one dimension
that is sufficiently small compared with the wavelength, a relatively
small number of iterations is required for convergence of the
simulation, and in addition, a small dipole interaction range can be
invoked to reduce the computation time to O(N) while still producing results that
are sufficiently accurate.
Funder
Israel Science Foundation
Subject
Atomic and Molecular Physics, and Optics,Engineering (miscellaneous),Electrical and Electronic Engineering