Nikolai A. Gippius

Symmetry breaking in a plasmonic metamaterial at optical wavelength

We numerically study the effect of structural asymmetry in a plasmonic metamaterial made from gold nanowires. It is reported that optically inactive (i.e., optically dark) particle plasmon modes of the symmetric wire lattice are immediately coupled to the radiation field, when a broken structural symmetry is introduced. Such higher order plasmon resonances are characterized by their subradiant nature. They generally reveal long lifetimes and distinct absorption losses. It is shown that the near-field interaction strongly determines these modes.

Polariton Effect in Distributed Feedback Microcavities

The excitonic and photonic states in distributed feedback (DFB) microcavities may strongly couple to form DFB cavity polaritons, provided that excitonic oscillator strength is large enough. In this paper we theoretically analyse the optical properties of DFB microcavities related to polariton effect. A numerical method based on scattering matrix formalism has been developed to solve the Maxwells equations for layered system with periodical patterning of layers. To incorporate polaritonic effect in our model we included the exciton poles in dielectric susceptibility of one of the patterned layers. Using this method we reproduce the characteristic features, demonstrated in recent experiments [Fujita et al.: Phys. Rev. B 57 (1998) 12428], such as anticrossing behavior of transmission dips in vicinity of the excitonic resonance and strong polarization dependence of their position and depth. ©2001 The Physical Society of Japan

Terahertz radiation due to random grating coupled surface plasmon polaritons

We report on terahertz (THz) radiation under electrical pumping from a degenerate semiconductor possessing an electron accumulation layer. In InN, the random grating formed by topographical defects provides high-efficiency coupling of surface plasmon polaritons supported by the accumulation layer to the THz emission. The principal emission band occupies the 2-6 THz spectral range. We establish a link between the shape of emission spectra and the structural factor of the random grating and show that the change of slope of power dependencies is characteristic for temperature-dependent plasmonic mechanisms. The super-linear rise of a THz emission intensity on applied electric power provides advantage of such materials in emission yield.

Trions in ZnSe‐Based Quantum Wells Probed by 50 T Magnetic Fields

Singlet and triplet states of negatively charged excitons (trions) in ZnSe/(Zn,Be,Mg)Se quantum wells have been studied by means of photoluminescence in pulsed magnetic fields up to 50 T. Singlet state binding energies, measured for different well widths ranging from 48 to 190 A, show a monotonic increase with growing magnetic fields with a tendency to saturation. This behavior is in qualitative agreement with results of model calculations. Quantitatively, the binding energy of singlet states is underestimated by about 50%. The triplet state assigned to the dark triplet becomes detectable in magnetic fields above 15 T. A crossover of the triplet and singlet states is expected in magnetic fields of about 50 T.

Linear and nonlinear optical properties of strongly coupled metal nanoparticles

Interaction of localized plasmons and propagating waveguide modes leads to strong coupling and polariton formation. These polaritons are the basis of nanoplasmonic effects in linear and nonlinear optics. Experiments, theory, and applications are presented.

Multifunction metal-semiconductor nanocomposites

The basic properties of metal-semiconductor nanocomposites were investigated using InN/In with In clusters as an example. Inconsistencies in the characteristic energies of optical processes occurring in these materials were revealed, and a model is proposed to describe the averaged enhancement by localized plasmons. The possibility of obtaining intense emission in the near infrared and terahertz ranges is demonstrated.

Interface (Tamm) minibands in superlattices

Properties of interface (Tamm) minibands are investigated within a physically illustrative, exactly soluble Kronig-Penney one-dimensional model of a superlattice. These minibands can easily be obtained within the envelope-function approximation provided the differences between band-edge Bloch functions of constituent layers are taken into account in the boundary conditions.

Symmetry breaking in a plasmonic metamaterial

We numerically study the optical properties of metal lattices made from periodically arranged plasmonic molecules, i.e., coupled gold nanowire pairs. It is shown that the interaction between the metallic wires, which is directly controlled by the specific lattice geometry, leads to the formation of collective surface plasmon modes. Surface plasmon hybridization is discussed and the direct influence of near- and far-field interaction are highlighted. In particular, it is shown that the common hybridization schema can be reversed by tuning the wire-wire interaction. Moreover, optical activity of higher order modes is demonstrated in case of symmetry breaking. An additional degree of freedom is introduced by inserting a homogeneous metal film, i.e., taking into account wire-image coupling.

Controlling the coupling between localized and delocalized surface plasmon modes in a metallic photonic crystal slab

We study the influence of controlled coupling between localized and delocalized surface plasmon modes on the transmission properties of metallic photonic crystals. The presented interaction phenomena are important for the optimization of future plasmonic nanodevices.

Optical properties of planar metallo-dielectric photonic crystal superlattices

We study experimentally and theoretically the influence of the superperiod on the transmission properties of metallic photonic crystals slabs. We found that additional modes couple to the plasmon resonances, leading to a strongly modified spectrum.