Anapole: Its birth, life, and death

Area of Science:

• Physics
• Optics
• Nanotechnology

Background:

• The nonradiating (anapole) mode in light scattering by nanoparticles is under extensive study.
• Key questions regarding the dynamics of anapole excitation and collapse remain unresolved.

Purpose of the Study:

• To investigate the dynamics of anapole mode excitation and collapse.
• To provide a comprehensive understanding of anapole behavior in light scattering phenomena.

Main Methods:

• Direct numerical integration of Maxwell equations for a dielectric cylinder scattering a rectangular laser pulse.
• Development of a simple, exactly integrable model for anapole dynamics.

Main Results:

• Anapole excitation and collapse share a characteristic timescale but exhibit qualitatively different dynamics.
• Excitation involves high-amplitude oscillatory modulations, while collapse shows monotonic envelope decay.
• The observed dynamics are generalizable to any classical system exhibiting anapole excitation.

Conclusions:

• The study clarifies the distinct excitation and collapse dynamics of the anapole mode.
• A novel, simple model is introduced, complementing existing theories like Temporal Coupled-Mode Theory.
• The findings offer broader insights into resonant phenomena in classical systems.