Perfect Absorption of a Focused Light Beam by a Single Nanoparticle

Absorption of electromagnetic energy by a dissipative material is one of the most fundamental electromagnetic processes that underlies a plethora of applied problems, including sensing, radar detection, wireless power transfer, and photovoltaics. Common wisdom is that a finite dissipative object illuminated by a plane wave removes only a finite amount of the wave's energy flux, which is determined by the object's absorption cross‐section. Thus, it is of fundamental interest to see if any far‐field waveform can be perfectly absorbed by a finite object. Here, it is theoretically demonstrated that a precisely tailored light beam containing only far‐field components can be perfectly absorbed by a finite scatterer on a substrate. The self‐consistent scattering problem in the dipole approximation is analytically solved and finds a closed‐form expression for the spatial spectrum of the incident field and the required complex polarizability of the particle. All analytical predictions are confirmed with full‐wave simulations. The results introduce a qualitatively novel class of perfect absorption phenomena in electromagnetics and other wave processes.