Natarov D. Plasmon and grating modes in scattering, absorption and emission of the optical waves by finite nanowire gratings

The object is the phenomena of scattering and absorption of plane electromagnetic waves by finite periodic gratings from circular material nanowires, as well as the emission of electromagnetic waves by open active resonators based on nanowires and gratings from them. The purpose of the research is to study the features and regularities of the scattering of plane electromagnetic waves by finite gratings from dielectric or silver nanowires of circular cross-section in the optical range, and to study of the eigenmodes of nanolasers based on silver nanowires and nanotubes with active shell and core and based on finite number quantum and silver with an active shell nanowires. The analysis is performed using the boundary value problems for linear time-harmonic Maxwell’s equations, which are reduces to the Fredholm second kind matrix equations, that guarantees controlled accuracy of numerical results. We study grating resonances in the scattering and absorption characteristics of the scattering problem, as well as the grating modes in the lasing eigenvalue problem, which correspond to the complex poles of the field function of a periodic structure. We demonstrate amplification of effects associated with periodicity with increasing number of periods in the grating, and compare finite and infinite gratings of nanowires. For stand-alone silver nanowires and gratings of them, we study plasmon resonances in the scattering problem and plasmon modes of nanolasers based on silver nanowires and nanotubes with active regions. We classify laser modes, analyze their near fields and the dependences of self-excitation thresholds and wavelengths on the parameters of a nanolaser.