Maxim Durach

Toward Full Spatiotemporal Control on the Nanoscale

We introduce an approach to implement full coherent control on nanometer length scales. It is based on spatiotemporal modulation of the surface plasmon polariton (SPP) fields at the thick edge of a nanowedge. The SPP wavepackets propagating toward the sharp edge of this nanowedge are compressed and adiabatically concentrated at a nanofocus, forming an ultrashort pulse of local fields. The profile of the focused waveform as a function of time and one spatial dimension is completely coherently controlled.

Metallization of Nanofilms in Strong Adiabatic Electric Fields

We introduce an effect of metallization of dielectric nanofilms by strong, adiabatically varying electric fields. The metallization causes optical properties of a dielectric film to become similar to those of a plasmonic metal (strong absorption and negative permittivity at low optical frequencies). This is a quantum effect, which is exponentially size-dependent, occurring at fields on the order of 0.1 V/Å and pulse durations ranging from ∼1 fs to ∼10 ns for a film thickness of 3-10 nm.

Predicted Ultrafast Dynamic Metallization of Dielectric Nanofilms by Strong Single-Cycle Optical Fields

We predict a dynamic metallization effect where an ultrafast (single-cycle) optical pulse with a ≲1 V/Å field causes plasmonic metal-like behavior of a dielectric film with a few-nm thickness. This manifests itself in plasmonic oscillations of polarization and a significant population of the conduction band evolving on a ~1 fs time scale. These phenomena are due to a combination of both adiabatic (reversible) and diabatic (for practical purposes irreversible) pathways.

Generation of isolated attosecond extreme ultraviolet pulses employing nanoplasmonic field enhancement: optimization of coupled ellipsoids

The production of extreme ultraviolet (XUV) radiation via nanoplasmonic field-enhanced high-harmonic generation (HHG) in gold nanostructures at MHz repetition rates is investigated theoretically in this paper. Analytical and numerical calculations are employed and compared in order to determine the plasmonic fields in gold ellipsoidal nanoparticles. The comparison indicates that numerical calculations can accurately predict the field enhancement and plasmonic decay, but may encounter difficulties when attempting to predict the oscillatory behavior of the plasmonic field. Numerical calculations for coupled symmetric and asymmetric ellipsoids for different carrier-envelope phases (CEPs) of the driving laser field are combined with time-dependent Schrodinger equation simulations to predict the resulting HHG spectra. The studies reveal that the plasmonic field oscillations, which are controlled by the CEP of the driving laser field, play a more important role than the nanostructure configuration in finding the optimal conditions for the generation of isolated attosecond XUV pulses via nanoplasmonic field enhancement.

Hyperbolic resonances of metasurface cavities

We propose a new class of optical resonator structures featuring one or two metasurface reflectors or metacavities and predict that such resonators support novel hyperbolic resonances. As an example of such resonances we introduce hyperbolic Tamm plasmons (HTPs) and hyperbolic Fabry-Perot resonances (HFPs). The hyperbolic optical modes feature low-loss incident power re-distribution over TM and TE polarization output channels, clover-leaf anisotropic dispersion, and other unique properties which are tunable and are useful for multiple applications.

On the nature of the plasmon drag effect

Light-matter momentum transfer in plasmonic materials is theoretically discussed in the framework of plasmonic pressure mechanism taking into account non-equilibrium electron dynamics and thermalization process. We show that our approach explains the experimentally observed relationship between the plasmon-related electromotive force and absorption and allows one to correctly predict the magnitude of the plasmon drag emf in flat metal films. We extend our theory to metal films with modulated profiles and show that the simple relationship between plasmonic energy and momentum transfer holds at relatively small amplitudes of height modulation and an approximation of laminar electron drift. Theoretical groundwork is laid for further investigations of shape-controlled plasmon drag in nanostructured metal.

Spin angular momentum transfer and plasmogalvanic phenomena

We introduce the continuity equation for the electromagnetic spin angular momentum (SAM) in matter and discuss the torque associated with the SAM transfer in terms of effective spin forces acting in a material. In plasmonic metal, these spin forces result in plasmogalvanic phenomenon which is pinning the plasmon-induced electromotive force to atomically-thin layer at the metal interface.

Collective plasmonic oscillations in gold nanostrips arrays

Excitation of collective plasmonic modes and their effect on optical behavior are experimentally and theoretically studied in 1D arrays of gold nanostrips in comparison with continuous gold films with periodically modulated profile. In strips, the angular dependence of the reflectivity demonstrates a peak at the resonance condition as opposed to a dip observed in continuous sine wave gratings. In addition, an extremely narrow feature in the reflection is observed in strips and tentatively ascribed to the bright Wood-Rayleigh anomaly. Theoretical calculations based on the combined transfer-matrix coupled-wave analysis and coordinate transformation method are shown to fit the experimental angular and spectral behavior of the plasmonic resonances. The effects are also discussed in terms of a simple equivalent circuit model.

Ultimately Thin Metasurface Wave Plates

Optical properties of a metasurface which can be considered a monolayer of uniaxial metamaterials - parallel-plate and nanorod arrays – are investigated. It is shown that such metasurface acts as an ultimately thin sub-100 nm wave plate. This is achieved via an interplay of epsilon-near-zero and epsilon-near-pole behavior along different axes in the plane of the metasurface allowing for extremely rapid phase difference accumulation in very thin metasurface layers. These effects are shown to not be disrupted by non-locality and can be applied to the design of ultrathin wave plates, Pancharatnam-Berry phase optical elements and plasmon-carrying optical torque wrench devices.

Theory of spoof plasmons in real metals

In this Letter we develop a theory of spoof plasmons propagating on real metals perforated with planar periodic grooves. Deviation from the spoof plasmons on perfect conductor due to finite skin depth has been analytically described. This allowed us to investigate important propagation characteristics of spoof plasmons such as quality factor and propagation length as the function of the geometrical parameters of the structure. We have also considered THz field confinement by adiabatic increase of the depth of the grooves. It is shown that the finite skin depth limits the propagation length of spoof plasmons as well as a possibility to localize THz field. Geometrical parameters of the structure are found which provide optimal guiding and localization of THz energy.