arXiv subjects

Vitalyi Gusev

Publications and source records attributed to Vitalyi Gusev.

7 recordsLinked to original sources

arXiv2026

Exciton-resonant detection of high-frequency surface acoustic waves from subwavelength metal gratings

We report on all-optical generation and detection of high-frequency (up to about 30 GHz) surface acoustic waves (SAWs) in GaAs/AlGaAs heterostructures with short-period Au gratings on top. A highly sensitive method for SAW detection is demonstrated using a polarization-resolved pump-probe technique that exploits the narrow exciton resonance in high-quality GaAs. The elastic strain of the SAW modulates the exciton energy in the time domain. As a result, even a small deformation produces a noticeable change in the dielectric function at the detection wavelength leading to an order of magnitude increase in the detection sensitivity as compared to off-resonant conditions. A theoretical model is developed that considers two detection schemes: one accounting for probe light diffraction and one corresponding to a non-diffractive situation.

cond-mat.mes-hall↗

arXiv2019

Acoustic Probing of the Jamming Transition in an Unconsolidated Granular Medium

Experiments with acoustic waves guided along the mechanically free surface of an unconsolidated granular packed structure provide information on the elasticity of granular media at very low pressures that are naturally controlled by the gravitational acceleration and the depth beneath the surface. Comparison of the determined dispersion relations for guided surface acoustic modes with a theoretical model reveals the dependencies of the elastic moduli of the granular medium on pressure. The experiments confirm recent theoretical predictions that relaxation of the disordered granular packing through non-affine motion leads to a peculiar scaling of shear rigidity with pressure near the jamming transition corresponding to zero pressure. Unexpectedly, and in disagreement with the most of the available theories, the bulk modulus depends on pressure in a very similar way to the shear modulus.

physics.class-ph↗

arXiv2019

Granular Graphene: direct observation of zigzag and armchair edge waves

We propose a mechanical granular graphene obtained by replacing the carbon atoms with macroscopic spherical stainless steel beads in contact. The experimental measured dispersion relation is presented, in conjunction with evidence of the Dirac points. In addition, wave propagation along the zigzag and a robust turning effect of edge waves from the zigzag to the armchair boundary is experimentally revealed, even in the absence of a full band gap for bulk modes. Our work shows that mechanical granular graphene can serve as an excellent experimental platform to study novel Dirac, topological and nonlinear wave phenomena.

physics.app-ph↗

arXiv2018

Ultrafast tunable modulation of light polarization at terahertz frequencies

Controlling light polarization is one of the most essential routines in modern optical technology. Since the demonstration of optical pulse shaping by spatial light modulators and its potential in controlling the quantum reaction pathways, it paved the way for many applications as a coherent control of the photoionization process or as polarization shaping of terahertz (THz) pulses. Here, we evidenced efficient nonresonant and noncollinear $χ^{(2)}$-type light-matter interaction in femtosecond polarization-sensitive time-resolved optical measurements. Such nonlinear optical interaction of visible light and ultrashort THz pulses leads to THz modulation of visible light polarization in bulk LiNbO$_3$ crystal. Theoretical simulations based on the wave propagation equation capture the physical processes underlying this nonlinear effect. Apart from the observed tunable polarization modulation of visible pulses at ultrahigh frequencies, this physical phenomenon can be envisaged in THz depth-profiling of materials.

physics.app-ph↗

arXiv2017

Time-domain Brillouin scattering assisted by diffraction gratings

Absorption of ultrashort laser pulses in a metallic grating deposited on a transparent sample launches coherent compression/dilatation acoustic pulses in directions of different orders of acoustic diffraction. Their propagation is detected by the delayed laser pulses, which are also diffracted by the metallic grating, through the measurement of the transient intensity change of the first order diffracted light. The obtained data contain multiple frequency components which are interpreted by considering all possible angles for the Brillouin scattering of light achieved through the multiplexing of the propagation directions of light and coherent sound by the metallic grating. The emitted acoustic field can be equivalently presented as a superposition of the plane inhomogeneous acoustic waves, which constitute an acoustic diffraction grating for the probe light. Thus, the obtained results can also be interpreted as a consequence of probe light diffraction by both metallic and acoustic gratings. The realized scheme of time-domain Brillouin scattering with metallic grating operating in reflection mode provides access to acoustic frequencies from the minimal to the maximal possible in a single experimental configuration for the directions of probe light incidence and scattered light detection. This is achieved by monitoring of the backward and forward Brillouin scattering processes in parallel. Applications include measurements of the acoustic dispersion, simultaneous determination of sound velocity and optical refractive index, and evaluation of the samples with a single direction of possible optical access.

physics.app-ph↗

arXiv2015

Elastic constants of polycrystalline steel evaluated with laser generated surface acoustic waves

We report on a laser generated and detected surface acoustic wave method for evaluating the elastic constants of micro-crystals composing polycrystalline steel. The method is based on the measurement of surface wave velocities in many micro-crystals oriented randomly relative to both the wave propagation direction and the sample surface. The surface wave velocity distribution is obtained experimentally thanks to the scanning potentiality of the method and is then compared to the theoretical one. The inverse problem can then be solved, leading to the determination of three elastic constants of the cubic symmetry micro-crystals. Extensions of the method to the characterization of texture, preferential orientation of micro-crystals or welds could be foreseen.

cond-mat.mtrl-sci↗

arXiv2008

Nonlinear effects for coda-type elastic waves in stressed granular media

Experimental results and their interpretations are presented on the nonlinear acoustic effects of multiple scattered elastic waves in unconsolidated granular media. Short wave packets with a central frequency higher than the so-called cut-off frequency of the medium are emitted at one side of the statically stressed slab of glass beads and received at the other side after multiple scattering and nonlinear interactions. Typical signals are strongly distorted compared to their initially radiated shape both due to nonlinearity and scattering. It is shown that acoustic waves with a deformation amplitude much lower than the mean static deformation of the contacts in the medium can modify the elastic properties of the medium, especially for the weak contact skeleton part. This addresses the problem of reproducibility of granular structures during and after acoustic excitation, which is necessary to understand in the non destructive testing of the elastic properties of granular media by acoustic methods. Coda signal analysis is shown to be a powerful time-resolved tool to monitor slight modifications in the elastic response of an unconsolidated granular structure.

physics.class-ph↗