Numerical study of light backscattering from layers of absorbing irregular particles larger than the wavelength

Abstract

We simulate light backscattering from monolayers of absorbing irregular particles larger than the wavelength using a numerically exact discontinuous Galerkin time domain (DGTD) method. Varying the real and imaginary parts of the complex refractive index m, particle size and the structure of a monolayer we study the evolution of the negative polarization (NP) feature that is observed for many particulate surfaces near backscattering. Simulations show that the NP is enhanced when increasing absorption from Im(m)=0.06 to 0.3. The real part Re(m) plays little role in this case. We confirm correlation of NP with the particle size predicted by approximate models and observed in laboratory measurements. We also demonstrate that the interplay between single- and multiple scattering can be controlled by the topography of a monolayer resulting in enhanced or damped NP.