Understanding light scattering by a coated sphere part 2: time domain analysis.

Area of Science:

• Electromagnetic theory
• Computational physics
• Optics

Background:

• Scattering of electromagnetic waves by dielectric spheres is a fundamental problem in optics.
• Previous studies have focused on homogeneous spheres or simplified models of coated spheres.
• Understanding scattering from coated spheres is crucial for applications in remote sensing, material science, and optical device design.

Purpose of the Study:

• To numerically compute and analyze the scattering of electromagnetic pulses by coated spheres.
• To investigate the influence of core and coating radii on scattering patterns.
• To identify and analyze the dominant Debye series terms contributing to scattered intensity.

Main Methods:

• Numerical computations using the Debye series expansion.
• Analysis of scattered intensity as a function of scattering angle and delay time.
• Examination of surface wave behavior at different interfaces.

Main Results:

• Identified dominant Debye series terms for different scattering regions.
• Observed the first-order rainbow evolving into three components with increasing core radius.
• Analyzed the merging of newly formed rainbow components.
• Discussed the behavior of surface waves at core/coating and coating/exterior interfaces.

Conclusions:

• The scattering characteristics of coated spheres are complex and depend significantly on the core and coating dimensions.
• The evolution of the first-order rainbow provides insights into the underlying scattering mechanisms.
• Surface waves play a notable role in the scattering process, particularly at grazing incidence.