Quantifying the coherent backscatter enhancement of nonspherical particles with discrete dipole approximation
Abstract
The prevailing backscattering peak associated with the scattering phase function of large nonabsorptive particles can be interpreted with the coherent backscatter enhancement (CBE) theory, but has not been explicitly quantified with numerical simulations based on solving Maxwell's equations. In this paper, representative numerical simulations performed with the discretedipoleapproximation (DDA) model are used to quantify the effect of CBE on the singlescattering phase function. For each scattering case, the particle volume was divided into multiple thin slices parallel to the incident beam. The dipole polarizations in the j'th slice in response to the incident field of the i'th slice were computed, and then the corresponding contribution to the scattering phase function was calculated. Interference between conjugate terms representing reversible wave paths is constructive at the backscattering direction, which corresponds to the CBE. Subsequently, the contribution of CBE to the scattering phase function was quantified by comparing the electric fields calculated with and without the interference between conjugate terms. Results from these numerical simulations are consistent with conclusions obtained from the CBE theory. The simulations also quantitatively explain why it is difficult to identify a CBEinduced backscattering peak for the phase function of small particles and strongabsorptive particles.
 Publication:

Optics Express
 Pub Date:
 July 2023
 DOI:
 10.1364/OE.494447
 Bibcode:
 2023OExpr..3124183Z