Search

A source which generates sustained terahertz electromagnetic radiation (oscillator) controllable by an applied voltage is proposed. The structure consists of a nanocomposite slab containing metal nanorods enclosed between two graphene sheets which are electrostatically gated. The principle of its operation is based on a positive feedback which the nanorods polarization experiences from the radiation reflected by the graphene mirrors. The proposed approach can provide a microscopic source of monochromatic polarized terahertz radiation of power sufficient for biomedical and security applications., Comment: 4 pages

The first-principles theory of lasing in a rectangular lattice of spherical metal nanoparticles is developed in a fully analytical form in the dipole approximation. The lasing conditions are obtained for different diffraction orders, both propagating and evanescent. Their analysis reveals that besides usual lasing there can be lasing without population inversion which is invisible in conventional experiments, but can be observed in total internal reflection., Comment: 6 pages

A theory of self-excitation in the metal-insulator-metal structure doped with metal nanowires is developed for the case where the power is provided by an external source of radio waves. Both the transient stage of self-excitation and the steady-state regime of self-oscillation are analyzed in a fully analytical form. The numerical estimates demonstrate that this effect can be used for diverse practical purposes, in particular, for radio frequency power harvesting. These findings extend the approach developed in nano-optics to the field of electrical engineering., Comment: 5 pages, 1 figure

A theory of lasing in an optically thin layer of active centers disposed at a metal surface is developed from first principles. The approach is based on a rigorous account of the local field in a close vicinity of a reflective surface which provides a feedback for dipole oscillations in active centers. It is demonstrated that the gain medium thickness plays a crucial role in the lasing condition and controls a switching from conventional lasing to lasing without inversion. The numerical calculations are carried out for erbium doped glass bordering a gold surface where radiation at telecom wavelength (1532 nm) can be generated., Comment: 9 pages, 3 figures. arXiv admin note: substantial text overlap with arXiv:2111.11746

A theory of lasing in a two-dimensional array of metal nanoparticles (MNPs) covered with a thin layer of fluorescent molecules is developed from first principles. The approach is based on a rigorous account of the local field in a close vicinity of a reflective surface which provides a feedback for molecular dipole oscillations. The theory predicts the lasing threshold in such an open cavity in terms of the polar angle of laser emission, MNPs shape and the molecular layer thickness. It is demonstrated that the latter parameter plays a crucial role in the lasing condition and controls a switching from conventional lasing to lasing without inversion. This research is inspired by recent experiments in this field [N. Toropov et al, Adv. Photonics Res. {\bf 2}, 2000083 (2021)] and provides the numerical calculations carried out for the experimental conditions., Comment: 8 pages, 6 figures

A theory of light reflection and transmission by an optically thin nanocomposite slab which contains randomly distributed metal nanoparticles (NPs) is developed. The underlying model takes into account the reflection of light scattered by NPs from the slab boundaries, enhanced decay of localized surface plasmons in dense NP arrays and light scattering at the slab surface -- the factors which are beyond the scope of the Maxwell Garnett approximation. It is demonstrated that the first two effects lead to broadband perfect absorption observed in such nanocomposites, whereas the last one is responsible for its omnidirectional character and polarization insensitivity. These findings open up new possibilities for engineering broadband perfect absorption in plasmonic nanocomposites., Comment: 11 pages, 12 figures

The Dicke superradiance from an optically thin nanocomposite slab represented by metal nanoparticles dispersed in a dielectric matrix is predicted and its theory is developed from first principles. It is shown that the superradiance signal evolution is determined by the eigenvalues of the field susceptibility tensor for the slab. The excitation of the system by a pumping pulse in different polarizations as well as in the attenuated total reflection configuration is considered. It is demonstrated that the relaxation rates are enhanced when surface plasmon polaritons are excited at the interface between the substrate and superstrate. These findings can pave a way to the extension of the optical techniques based on the Dicke superradiance to the femtosecond time domain., Comment: 7 pages, 4 figures

Single-photon sources are subjected to a fundamental limitation in the speed of operation dictated by the spontaneous emission rate of quantum emitters (QEs). The current paradigm of the rate acceleration suggests coupling of a QE to a metal nanostructure, in particular, a metal nanoparticle (MNP). Here, we demonstrate that, in contrast to this approach, a MNP itself can behave as a quantum emitter. We determine both the first- and second-order correlation functions of light spontaneously emitted by a MNP strongly coupled to a QE and show that this light should exhibit sub-Poissonian photon statistics and perfect photon antibunching. This discovery opens a prospect to single-photon sources with unprecedented generation rates up to 100 THz., Comment: 5 pages, 3 figures

The concept of quantum plasmonic excitations in plasmonic lattices, which similarly to Frenkel excitons in molecular crystals propagate by hopping from one nanoparticle to another, is introduced. A consistent quantum theory of such plasmonic excitons, beginning with the quantization of localized surface plasmons in a metal nanoparticle and including the radiative relaxation in both 1D and 2D lattices near a reflective substrate surface, is developed. A possible room-temperature Bose-Einstein condensation in the quantum gas of plasmonic excitons is also discussed., Comment: 11 pages, 3 figures

We propose a generator of surface plasmon polaritons (SPPs) which, unlike spasers or plasmon lasers, does not require stimulated emission in the system. Its principle of operation is based on a positive feedback which a classical oscillating dipole experiences from a reflective surface located in its near field. The generator design includes a nanocavity between two metal surfaces which contains metal nanoparticles in its interior. The whole structure is placed onto a prism surface that allows one to detect the generated SPPs in the Kretschmann configuration. The generation process is driven by a moderate constant voltage applied between the metal covers of the cavity. Both the generation criterion and the steady-state operation of the generator are discussed., Comment: 5 pages, 2 figures

The novel effect of self-excitation of surface plasmons (SESP) in a plasmonic nanocavity is predicted and its theory is developed from first principles. It is assumed that the cavity is formed by a nanogap between two metals and contains polarizable inclusions. Basing on the dyadic Green's function of the structure, the equations for the field in the cavity are investigated. It is shown that under certain conditions the field becomes unstable that leads to its self-excitation. The threshold criterion for self-excitation as well as the frequency of self-oscillation are derived in an analytical form. The SESP effect is explained in terms of a positive feedback for the polarization of inclusions provided by the field reflected from the cavity walls. Such a mechanism does not imply stimulated emission that distinguishes it from SPASER or plasmon laser., Comment: 5 pages, 2 figures