Higher-order resonant power flow inside and around superdirective plasmonic nanoparticles

摘要

The optical power flow around a plasmonic particle has been a topic of research interest over the years [see e.g., Am. J. Phys: 51, 323 (1983); Opt. Express 13, 8372 (2005)]. Here we revisit this problem with an emphasis on higher-order resonances, and we present the theoretical results of our analysis for such power-flow distribution for plasmonic nanoparticles at their multipolar resonances. Results for the second and third orders of resonance show optical power-flow patterns that are significantly different from that of the first-order resonance inside and around plasmonic superdirective nanoparticles, with multicenter vortices, saddle points, and saddle lines and with an anomalous circulation of power resembling higher-order modes in a resonant cavity. A potential application of these optical flow patterns to trap or move a neighboring nanoparticle is also briefly suggested.