Maxim Sukharev - Academia.edu (original) (raw)

Papers by Maxim Sukharev

We examine the coupling of electromagnetic waves entering a thin silver film that forms an oscill... more We examine the coupling of electromagnetic waves entering a thin silver film that forms an oscillatory grating embedded between two otherwise uniform semi-infinite half spaces having identical dielectric constants. On reducing the grating period from the long wavelength limit we encounter signatures in the transmission, T, and reflection, R, coefficients associated with: 1) the symmetric surface mode, 2) the anti-symmetric

The Journal of chemical physics, Jan 14, 2015

Shaped ultrafast laser pulses were used to study and control the ionization dynamics of electroni... more Shaped ultrafast laser pulses were used to study and control the ionization dynamics of electronically excited pyrazine in a pump and probe experiment. For pump pulses created without feedback from the product signal, the ion growth curve (the parent ion signal as a function of pump/probe delay) was described quantitatively by the classical rate equations for internal conversion of the S2 and S1 states. Very different, non-classical behavior was observed when a genetic algorithm (GA) employing phase-only modulation was used to minimize the ion signal at some pre-determined target time, T. Two qualitatively different control mechanisms were identified for early (T < 1.5 ps) and late (T > 1.5 ps) target times. In the former case, the ion signal was largely suppressed for t < T, while for t ≫ T, the ion signal produced by the GA-optimized pulse and a transform limited (TL) pulse coalesced. In contrast, for T > 1.5 ps, the ion growth curve followed the classical rate equatio...

Nano letters, 2006

We extend the concepts of phase, polarization, and feedback control of matter to develop a genera... more We extend the concepts of phase, polarization, and feedback control of matter to develop a general approach for guiding light in the nanoscale via nanoparticle arrays. The phase and polarization of the excitation source are first introduced as tools for control over the pathway of light at array intersections. Genetic algorithms are next applied as a systematic design tool, wherein both the excitation field parameters and the structural parameters of the nanoparticle array are optimized to make devices with desired functionality. Implications to research fields such as single molecule spectroscopy, spatially confined chemistry, optical logic, and nanoscale sensing are envisioned.

$Research paper thumbnail of Numerical analysis of a slit-groove diffraction problem$

We present a comparison among several fully-vectorial methods applied to a basic scattering probl... more We present a comparison among several fully-vectorial methods applied to a basic scattering problem governed by the physics of the electromagnetic interaction between subwavelength apertures in a metal film. The modelled structure represents a slit-groove scattering problem in a silver film deposited on a glass substrate. The benchmarked methods, all of which use in-house developed software, include a broad range of fully-vectorial approaches from finite-element methods, volume-integral methods, and finite-difference time domain methods, to various types of modal methods based on different expansion techniques.

Physical Review Letters, 2014

We determine the optical response of a thin and dense layer of interacting quantum emitters. We s... more We determine the optical response of a thin and dense layer of interacting quantum emitters. We show that in such a dense system, the Lorentz redshift and the associated interaction broadening can be used to control the transmission and reflection spectra. In the presence of overlapping resonances, a Dipole-Induced Electromagnetic Transparency (DIET) regime, similar to Electromagnetically Induced Transparency (EIT), may be achieved. DIET relies on destructive interference between the electromagnetic waves emitted by quantum emitters. Carefully tuning material parameters allows to achieve narrow transmission windows in otherwise completely opaque media. We analyze in details DIET using a generalized Lorentz model and show how it can be controlled. Several potential applications of the phenomenon are proposed.

Journal of Physical Chemistry C, 2008

We present theoretical models and experiments demonstrating nanoparticle optical birefringence. T... more We present theoretical models and experiments demonstrating nanoparticle optical birefringence. The experiments use polarization optical methods to describe the birefringence properties of two-dimensional arrays of L-shaped silver nanoparticles. These particles have two major resonances with perpendicular polarization directions. The beam depolarization at incident angles intermediate to the resonance polarization directions is explained with a model based on a finite-difference time-domain (FDTD) calculation for both arrays and single particles. The maximum relative phase retardation is observed between the two overlapping dipole resonance wavelengths, and experimentally it is about 30°. While the FDTD models predict a larger effect of up to 105°, this might be due to the statistical variation of nanoparticle shapes in the experimental arrays. The arrays were fabricated by electron beam lithography, and the size of particles was ∼145 and ∼155 nm in nominal total edge length, 63 nm arm width, and 30 nm height. The observed phase difference is large compared to the conventional birefringence materials with the same thickness. This study suggests the possible application of two-dimensional nanoparticle arrays or single particles as wavelength-tunable, extremely thin birefringence materials.

The Journal of Physical Chemistry A, 2009

We develop a full 3D approach to simulate the optical properties of sharp metal tips that could b... more We develop a full 3D approach to simulate the optical properties of sharp metal tips that could be quantitatively compared with experiments and provide accurate predictions. Similar to metallic wires, elongated metal tips support a series of extended mode resonances whose properties are largely determined by the tip geometry and are essentially independent of the tip material. For sufficiently long tips, these resonances are energetically well separated from a broader, high-energy feature, whose position and line shape are independent of the tip length but vary strongly with the tip material. The latter is a localized plasmon mode characterized by the hemisphere terminating the tip.

Quantum Electronics, 2002

A revised, more comprehensive model of excitation and propagation of acoustic vibrations, electro... more A revised, more comprehensive model of excitation and propagation of acoustic vibrations, electrostrictively induced in optical ébres by laser pulses, is presented. An analytic expression for the acoustic response function of the refractive index in a standard single-mode ébre is derived. Response functions are found for a standard ébre as well as for a single-mode double-clad ébre, which offers much promise for ébreoptic communication lines and where the effective area of mode-éeld cross section is increased with respect to a standard ébre. It is shown that the intensity of excited sound waves in double-clad ébres is usually several times higher than that in standard ébres. This intensity is determined mainly by the shape of the radial distribution of the electromagnetic éeld in the pulse, which is different for the ébres considered in this paper.

Physical Review Letters, 2008

An ultrafast, nanoscale molecular switch is proposed, based on extension of the concept of nonadi... more An ultrafast, nanoscale molecular switch is proposed, based on extension of the concept of nonadiabatic alignment to surface-adsorbed molecules. The switch consists of a conjugated organic molecule adsorbed onto a semiconducting surface and placed near a scanning tunneling microscope tip. A low-frequency, polarized laser field is used to switch the system by orienting the molecule with the field polarization axis, enabling conductance through the junction. Enhancement and spatial localization of the incident field by the metallic tip allow operation at low intensities. The principles of nonadiabatic alignment lead to switch on and off time scales far below rotational time scales.

Physical Review Letters, 2004

We propose a general approach for eliminating radiationless transitions in polyatomic molecules a... more We propose a general approach for eliminating radiationless transitions in polyatomic molecules and illustrate it through the example of the S2--&amp;amp;amp;amp;amp;gt;S1 internal conversion of pyrazine. Essential to our approach is the phenomenon of electronically localized eigenstates of strongly vibronically coupled Hamiltonians. The occurrence of such states, observed here for the first time, and its generality are traced to the origin of scars of periodic orbits.

Physical Review Letters, 2012

We demonstrate strong coupling between molecular excited states and surface plasmon modes of a sl... more We demonstrate strong coupling between molecular excited states and surface plasmon modes of a slit array in a thin metal film. The coupling manifests itself as an anti-crossing behavior of the two newly formed polaritons. As the coupling strength grows, a new mode emerges, which is attributed to long range molecular interactions mediated by the plasmonic field. The new, molecular-like mode repels the polariton states, and leads to an opening of energy gaps both below and above the asymptotic free molecule energy.

Physical Review E, 2007

Using transmission electron microscopy (TEM) to analyse the physical-chemical surface properties ... more Using transmission electron microscopy (TEM) to analyse the physical-chemical surface properties of subwavlength structured silver films and finite-difference time-domain (FDTD) numerical simulations of the optical response of these structures to plane-wave excitation, we report on the origin and nature of the persistent surface waves generated by a single slit-groove motif and recently measured [1] by far-field optical interferometry. The surface analysis shows that the silver films are free of detectable oxide or sulfide contaminants, and the numerical simulations show very good agreement with the results previously reported.

Physical Review B, 2011

We consider a two-level system coupled to contacts as a model for a charge pump under external la... more We consider a two-level system coupled to contacts as a model for a charge pump under external laser pulse. The model represents a charge-transfer molecule in a junction and is a generalization of previously published results [B. D. Fainberg, M. Jouravlev, and A. Nitzan, Phys. Rev. B 76, 245329 (2007)]. Effects of local field for realistic junction geometries and non-Markov response of the molecule are taken into account within finite-difference time-domain and on-the-contour equation-of-motion formulations, respectively. We find that contrary to the symmetric behavior of the pump relative to the chirp sign, the duration of the corresponding local-field pulse does depend on the chirp sign, which results in an asymmetric charge pumping. The most effective charge-pump regime is found at positive bias, contrary to Markov consideration of the previous study.

Physical Review B, 2007

We present theoretical and experimental studies of the optical response of L-shaped silver nanopa... more We present theoretical and experimental studies of the optical response of L-shaped silver nanoparticles. The scattering spectrum exhibits several plasmon resonances that depend sensitively on the polarization of the incident electromagnetic field. The physical origin of the resonances is traced to different plasmon phenomena. In particular, a high energy band with unusual properties is interpreted in terms of volume plasmon oscillations arising from the asymmetry of a nanoparticle.

Physical Review A, 2002

We have performed nonperturbative time-dependent calculations of single and double ionization of ... more We have performed nonperturbative time-dependent calculations of single and double ionization of atomic calcium by short and intense laser pulses using a two-active-electron model. It is shown that the significant enhancement of the Ca 2ϩ yield observed in a recent experiment ͓E. Papastathopulous, M. Strehle, and G. Gerber ͑unpublished͔͒ using feedback control techniques originates from the time asymmetry of the pulse shape. Numerical simulations have been performed for various asymmetrical pulses. The initial part of the pulse prepares a coherent superposition of excited states which is transferred into the double-electron continuum at later times. An asymmetric shape, with a slowly decreasing tail, therefore favors the production of Ca 2ϩ . Single-active-electron calculations have also been performed to demonstrate the significant role played by electron correlations and by doubly excited states.

Physical Review A, 2005

We propose an approach for elimination of radiationless transitions in the excited states of poly... more We propose an approach for elimination of radiationless transitions in the excited states of polyatomic molecules. Our method is based on the concept of electronically localized eigenstates of coupled vibronic Hamiltonians-the occurrence of stationary eigenfunctions of essentially pure electronic character in the ͑otherwise strongly mixed͒ spectra of excited manifold Hamiltonians of systems undergoing nonradiative decay. The origin of this phenomenon and its generality are explained within the framework of the theory of scars of unstable periodic orbits. Optimal control theory is combined with the notion of electronically localized states to prepare the system in an excited superposition that is immune to nonradiative decay. The approach is applied to suppress ultrafast radiationless transitions in two model systems that differ widely in coupling strength and electronic structure.

Optics Letters, 2000

We have theoretically investigated, for what is to our knowledge the f irst time, the electrostri... more We have theoretically investigated, for what is to our knowledge the f irst time, the electrostrictive response in a single-mode ring-core f iber. We found that the electrostrictive response function differs strongly from those of standard f ibers with a Gaussian light-intensity prof ile. 

Optics Letters, 2010

We have fabricated line gratings from periodically etched fused silica on which a thin silver fil... more We have fabricated line gratings from periodically etched fused silica on which a thin silver film is deposited that is in turn covered with a silica index-matched fluid. This dielectrically symmetric geometry supports an independent long-range surface plasmon-polariton (LRSPP) and a short-range surface plasmon polariton, and the associated plasmonic band structure has been probed. Coupling to external light is achieved via the patterned grating, and an ultrasharp LRSPP linewidth of 4 nm is observed. The experimental results are compared with finite-difference time-domain simulations.