We demonstrate the possibility of the optical orientation of excitons in the near field of the metal grating that covers a semiconductor nanostructure. Excitons generated this way have the wave vector greater than the wave vector of the incident radiation. We suggest that optical orientation method is applicable to study the fine structure and kinetics of the hot excitons in semiconductor quantum well.

Deceleration of terahertz (THz) plasma waves (plasmons) in tapered structure with graphene layer pumped by optical plasmons is studied theoretically. It is shown, that THz plasma wave is decelerated when moving toward the structure apex. Deceleration of THz plasmons in tapered structure with graphene layer pumped by optical plasmons is more efficient as compared to deceleration of THz plasmons in tapered structure with graphene screened by metal without pumping by optical plasmons for the same parameter values of the structure. The plasmon phase velocity near the taper apex can become an order of magnitude smaller as compared to that value in the input of the structure for achievable power densities of the optical plasmon.

Theory of plasmon-exciton coupling is developed for a metal nanocylinder grating located in the vicinity of a semiconductor quantum well. In dipole approximation, the effective polarizability of cylinders is derived, taking into account generation of quantum-well excitons in the near field of surface plasmons. Given the polarizability, the spectra of reflection and absorption are calculated for metal-semiconductor systems to study the effect of plasmon-exciton interaction. The excitonic response is shown to be enhanced by high-quality plasmons of Ag cylinders, although strong coupling is not attained for realistic nanostructure parameters.

The structure of the optical spectra related to the resonant interaction of quasi-two-dimensional excitons and localized plasmons is investigated theoretically. The constant of plasmon–exciton coupling is estimated in a model considering a semiconductor quantum well close to a layer of metal nanoparticles in an adjacent dielectric medium. Numerical calculations carried out for GaAs/Ag and ZnO/Al nanosystems indicate that near the plasmon–exciton resonance the spectrum features a double-peak structure which exhibits the plasmon-excitonic anticrossing behavior upon detuning from exact resonance.

AbstractThe structure of the optical spectra related to the resonant interaction of quasi-two-dimensional excitons and localized plasmons is investigated theoretically. The constant of plasmon–exciton coupling is estimated in a model considering a semiconductor quantum well close to a layer of metal nanoparticles in an adjacent dielectric medium. Numerical calculations carried out for GaAs/Ag and ZnO/Al nanosystems indicate that near the plasmon–exciton resonance the spectrum features a double-peak structure which exhibits the plasmon-excitonic anticrossing behavior upon detuning from exact resonance.

A theory of plasmonic reflectance anisotropy spectroscopy (RAS) is developed for nanocluster layer at an interface. The model of identical ellipsoidal metal particles occupying the sites of rectangular lattice is used to calculate the effective plasmonic polarizability of nanoparticles. The anisotropic local field due to optically induced dipole plasmons and their interface-conditioned images is taken into account. Within the theory, resonant reflectance anisotropy spectra recently observed for In nanoclusters on InAs surface are explained, the anisotropy being associated with the difference between frequencies of plasmons with orthogonal in-layer polarizations. The frequency difference is treated in terms of anisotropy of the particles shape or/and the layer structure, its sign being opposite for the two types of anisotropy. The plasmonic RAS is concluded to serve as a method for investigating the anisotropy of nanocluster arrays.

Представлена теория дифференциального анизотропного отражения света от наночастиц, обладающих плазмонами и находящихся вблизи границы раздела сред. Рассматривается модель монослоя одинаковых металлических частиц эллипсоидальной формы, заполняющих узлы прямоугольной решетки. Методом функций Грина в самосогласованном приближении квазиточечных диполей вычислены эффективные плазмонные поляризуемости наночастиц в слое. Учитывается эффект локального поля, обусловленный анизотропными дипольными плазмонами частиц слоя и диполями их изображения. Наблюдавшиеся недавно резонансные спектры анизотропного отражения света от нанокластеров индия на поверхности InAs объясняются различием частот, принадлежащих плазмонам с ортогональными поляризациями в плоскости поверхности. Показано, что различие плазмонных частот может быть связано с анизотропией формы частиц или/и структуры слоя, причем знак разности частот различен для этих двух типов анизотропии.

A theory of plasmonic differential anisotropic reflection of light from nanoparticles located near the interface between media is developed. The model of a monolayer consisting of identical ellipsoidal metal particles occupying sites of a rectangular lattice is investigated. Effective plasmonic polarizabilities of nanoparticles in the layer are calculated self-consistently using the Green’s function technique in the quasipoint dipole approximation. The local-field effect caused by anisotropic dipole plasmons of particles in the layer and their image dipoles is taken into account. The lately observed resonant reflectance anisotropy spectra of indium nanoclusters on InAs surface are explained by the difference between frequencies of plasmons with the orthogonal polarizations in the surface plane. The difference between the plasmon frequencies is attributed to anisotropy of the particles shape or/and the layer structure; the signs of frequency difference for the two types of anisotropy being different.

We have studied the emission of terahertz radiation from nanoporous semiconductor matrices of GaP excited by the femtosecond laser pulses. We observe 3-4 orders of magnitude increase of terahertz radiation emission from the nanoporous matrix compared to bulk material.

In this paper, we have studied the emission of terahertz radiation from nanoporous semiconductor matrices of GaP excited by the femtosecond laser pulses. We observe 3–4 orders of magnitude increase of terahertz radiation emission from the nanoporous matrix compared to bulk material. The effect is mainly related to drastic increase of the sample surface and pinning of conducting electrons to surface states. This result opens up a promising way to create powerful sources of terahertz radiation using nanoporous semiconductors.