arXiv subjects

Ilya V. Shadrivov

Publications and source records attributed to Ilya V. Shadrivov.

At least 19 recordsLinked to original sources

arXiv2025

Parametric metasurfaces for amplified up-conversion of electromagnetic waves

Spatiotemporal metasurfaces, characterized by dynamic variations in both space and time, enable functionalities unattainable with passive metasurfaces. In this study, we propose a novel concept of parametric metasurfaces capable of performing frequency up-conversion and amplification of free-space electromagnetic waves. This functionality is realized through the modulation of variable capacitances embedded in specially designed dual split-ring resonators. We explore various combinations of the pump and incident wave frequencies and investigate different operational regimes of the proposed parametric system. Our theoretical analysis reveals high up-conversion efficiency, with amplification levels exceeding 20 dB through a cascaded process, surpassing the limits set by the Manley-Rowe relations. Moreover, precise control over the phase of the up-converted waves is achieved by tuning the pump phase, paving the way for advanced manipulation of electromagnetic waves. This approach is applicable in the microwave and subterahertz ranges, with potential scalability to higher frequencies through ultrafast modulation techniques.

physics.optics↗

arXiv2024

Active Control of Bound States in the Continuum in Toroidal Metasurfaces

The remarkable properties of toroidal metasurfaces, featuring ultrahigh-Q bound states in the continuum (BIC) resonances and nonradiating anapole modes, have garnered significant attention. The active manipulation of quasi-BIC resonance characteristics offers substantial potential for advancing tunable metasurfaces. Our study explores explicitly the application of vanadium dioxide, a phase change material widely used in active photonics and room-temperature bolometric detectors, to control quasi-BIC resonances in toroidal metasurfaces. The phase change transition of vanadium dioxide occurs in a narrow temperature range, providing a large variation in material resistivity. Through heating thin film patches of vanadium dioxide integrated into a metasurface comprising gold split-ring resonators on a sapphire substrate, we achieve remarkable control over the amplitude and frequency of quasi-BIC resonances due to their high sensitivity to losses present in the system. Breaking the symmetry of meta-atoms reveals enhanced tunability. The predicted maximum change in the quasi-BIC resonance amplitude reaches 14 dB with a temperature variation of approximately 10 °C.

physics.optics↗

arXiv2024

Parametric metasurfaces for electromagnetic wave amplification

We study parametric amplification of electromagnetic waves using metasurfaces. We design a variable capacitor-loaded metasurface that can amplify incident electromagnetic waves. We analyze various regimes of operation of the system and find that we can achieve a significant gain (over 10 dB) in just one layer of such a structure, and this gain can be controlled by parametric modulation. We study the instability threshold for this system and show that a simple theoretical model agrees well with the results of full numerical simulations.

physics.app-ph↗

arXiv2019

Time-varying metasurfaces for broadband spectral camouflage

The possibility of making an object invisible for detectors has become a topic of considerable interest over the past decades. Most of the studies so far focused on reducing the visibility by reshaping the electromagnetic scattering in the spatial domain. In fact, by manipulating the electromagnetic scattering in the time domain, the visibility of an object can also be reduced. Importantly, unlike previous studies on phase-switched screens and time-varying metasurfaces, where the effect is narrow band due to the dispersive resonance, for microwave frequency range, we introduce a broadband switchable metasurface integrated with p-i-n diodes. The reflection phase of the metasurface can be changed by approximately π over a fractional bandwidth of 76%. By modulating the metasurface quasirandomly in the time domain, the incident narrow-band signal is spread into a white-noiselike spectrum upon reflection, creating a spectral camouflage. The broadband feature of the proposed time-varying metasurface can provide practical insight for various applications, including radar stealth and ultrawide-band wireless communication.

physics.app-ph↗

arXiv2018

Refraction efficiency of Huygens' and bianisotropic terahertz metasurfaces

Metasurfaces are an enabling technology for complex wave manipulation functions, including in the terahertz frequency range, where they are expected to advance security, imaging, sensing, and communications technology. For operation in transmission, Huygens' metasurfaces are commonly used, since their good impedance match to the surrounding media minimizes reflections and maximizes transmission. Recent theoretical work has shown that Huygens' metasurfaces are non-optimal, particularly for large angles of refraction, and that to eliminate reflections and spurious diffracted beams it is necessary to use a bianisotropic metasurface. However, it remains to be demonstrated how significant the efficiency improvement is when using bianisotropic metasurfaces, considering all the non-ideal features that arise when implementing the metasurface design with real meta-atoms. Here we compare concrete terahertz metasurface designs based on the Huygens' and Omega-type bianisotropic approaches, demonstrating anomalous refraction angles for 55 degrees, and 70 degrees. We show that for the lower angle of 55 degrees, there is no significant improvement when using the bianisotropic design, whereas for refraction at 70 degrees the bianisotropic design shows much higher efficiency and fidelity of refraction into the designed direction. We also demonstrate the strong perturbations caused by near-field interaction, both between and within cells, which we compensate using numerical optimization.

physics.app-ph↗

arXiv2018

Time-varying Huygens' meta-devices for parametric waves

Huygens' metasurfaces have demonstrated almost arbitrary control over the shape of a scattered beam, however, its spatial profile is typically fixed at fabrication time. Dynamic reconfiguration of this beam profile with tunable elements remains challenging, due to the need to maintain the Huygens' condition across the tuning range. In this work, we experimentally demonstrate that a time-varying metadevice which performs frequency conversion can steer transmitted or reflected beams in an almost arbitrary manner, with fully dynamic control. Our time-varying Huygens' metadevice is made of both electric and magnetic meta-atoms with independently controlled modulation, and the phase of this modulation is imprinted on the scattered parametric waves, controlling their shapes and directions. We develop a theory which shows how the scattering directionality, phase and conversion efficiency of sidebands can be manipulated almost arbitrarily. We demonstrate novel effects including all-angle beam steering and frequency-multiplexed functionalities at microwave frequencies around 4 GHz, using varactor diodes as tunable elements. We believe that the concept can be extended to other frequency bands, enabling metasurfaces with arbitrary phase pattern that can be dynamically tuned over the complete 2πrange.

physics.app-ph↗

arXiv2016

Tunable Focusing by a Flexible Metasurface

An efficient reflective elastic metasurface with tunable focusing point is proposed. The metasurface is based on electric resonators embedded in a stretchable elastic substrate. The focal length is controlled by mean of the stretching applied applied to the sample. The results predicted by theory and numerical simulations are experimentally verified. Our proposal shows that smart engineering elastic metamaterials are an effective platform for new functional devices based on metamaterials.

physics.optics↗

arXiv2014

Dispersionless optical activity in metamaterials

We introduce a chiral metamaterial with strong, non-resonant optical activity, and very low polarization ellipticity. We achieve this by combining a meta-atom and its complementary structure into a meta-molecule, resulting in the coupling of magnetic and electric dipole responses. In contrast to either a pair of crosses, or complementary crosses, this structure has low dispersion in the optical activity at the transmission resonance. We also study the excitation mechanism in this structure, and optimize the optical activity through changing the twist angle.

physics.optics↗

arXiv2014

Broadband chiral metamaterials with large optical activity

We study theoretically and experimentally a novel type of metamaterial with hybrid elements composed of twisted pairs of cross-shaped meta-atoms and their complements. We reveal that such two-layer metasurfaces demonstrate large, dispersionless optical activity at the transmission resonance accompanied by very low ellipticity. We develop a retrieval procedure to determine the effective material parameters for this structure, which has lower-order symmetry ($\mathrm {C}_4$) than other commonly studied chiral structures. We verify our new theoretical approach by reproducing numerical and experimental scattering parameters.

physics.optics↗

arXiv2013

Dissipative plasmon-solitons in multilayer graphene

Nonlinear properties of a multi-layer stack of graphene sheets are studied. It is predicted that such a structure may support dissipative plasmon-solitons generated and supported by an external laser radiation. Novel nonlinear equations describing spatial dynamics of the nonlinear plasmons driven by a plane wave in the Otto configuration are derived and the existence of single and multi-hump dissipative solitons in the graphene structure is predicted.

physics.optics↗

arXiv2013

Twists and turns for metamaterials

We propose and verify experimentally a new concept for achieving strong nonlinear coupling between the electromagnetic and elastic properties in metamaterials. This coupling is provided through a novel degree of freedom in metamaterial design: internal rotation within structural elements. Our meta-atoms have high sensitivity to electromagnetic wave power, and the elastic and electromagnetic properties can be independently designed to optimise the response. We demonstrate a rich range of nonlinear phenomena including self-tuning and bistability, and provide a comprehensive experimental demonstration of the predicted effects.

physics.optics↗

arXiv2012

Tuning the Nonlinear Response of Coupled Split-Ring Resonators

We introduce the concept of controlling the nonlinear response of the metamaterial by altering its internal structure. We experimentally demonstrate tuning of the nonlinear response of two coupled split-ring resonators by changing their mutual position. This effect is achieved through modification of the structure of the coupled resonant modes, and their interaction with the incident field. By offsetting the resonators we control the maximum currents through the nonlinear driving elements, which affects the nonlinear response of the system.

physics.optics↗

arXiv2012

Anderson localization in metamaterials and other complex media

We review some recent (mostly ours) results on the Anderson localization of light and electron waves in complex disordered systems, including: (i) left-handed metamaterials, (ii) magneto-active optical structures, (iii) graphene superlattices, and (iv) nonlinear dielectric media. First, we demonstrate that left-handed metamaterials can significantly suppress localization of light and lead to an anomalously enhanced transmission. This suppression is essential at the long-wavelength limit in the case of normal incidence, at specific angles of oblique incidence (Brewster anomaly), and in the vicinity of the zero-epsilon or zero-mu frequencies for dispersive metamaterials. Remarkably, in disordered samples comprised of alternating normal and left-handed metamaterials, the reciprocal Lyapunov exponent and reciprocal transmittance increment can differ from each other. Second, we study magneto-active multilayered structures, which exhibit nonreciprocal localization of light depending on the direction of propagation and on the polarization. At resonant frequencies or realizations, such nonreciprocity results in effectively unidirectional transport of light. Third, we discuss the analogy between the wave propagation through multilayered samples with metamaterials and the charge transport in graphene, which enables a simple physical explanation of unusual conductive properties of disordered graphene superlatices. We predict disorder-induced resonances of the transmission coefficient at oblique incidence of the Dirac quasiparticles. Finally, we demonstrate that an interplay of nonlinearity and disorder in dielectric media can lead to bistability of individual localized states excited inside the medium at resonant frequencies. This results in nonreciprocity of the wave transmission and unidirectional transport of light.

physics.optics↗

arXiv2011

Discrete dissipative localized modes in nonlinear magnetic metamaterials

We analyze the existence, stability, and propagation of dissipative discrete localized modes in one- and two-dimensional nonlinear lattices composed of weakly coupled split-ring resonators (SRRs) excited by an external electromagnetic field. We employ the near-field interaction approach for describing quasi-static electric and magnetic interaction between the resonators, and demonstrate the crucial importance of the electric coupling, which can completely reverse the sign of the overall interaction between the resonators. We derive the effective nonlinear model and analyze the properties of nonlinear localized modes excited in one- and two-dimensional lattices. In particular, we study nonlinear magnetic domain walls (the so-called switching waves) separating two different states of nonlinear magnetization, and reveal the bistable dependence of the domain wall velocity on the external field. Then, we study two-dimensional localized modes in nonlinear lattices of SRRs and demonstrate that larger domains may experience modulational instability and splitting.

physics.optics↗

arXiv2011

Metamaterials with conformational nonlinearity

Within a decade of fruitful developments, metamaterials became a prominent area of research, bridging theoretical and applied electrodynamics, electrical engineering and material science. Being man-made structures, metamaterials offer a particularly useful playground to develop novel interdisciplinary concepts. Here we demonstrate a novel principle in metamaterial assembly which integrates electromagnetic, mechanical, and thermal responses within their elements. Through these mechanisms, the conformation of the meta-molecules changes, providing a dual mechanism for nonlinearity and offering nonlinear chirality. Our proposal opens a wide road towards further developments of nonlinear metamaterials and photonic structures, adding extra flexibility to their design and control.

physics.optics↗

arXiv2011

Magnetoelastic nonlinear metamaterials

We introduce the concept of magnetoelastic metamaterials with electromagnetic properties depending on elastic deformation. We predict a strong nonlinear and bistable response of such metamaterials caused by their structural reshaping in response to the applied electromagnetic field. In addition, we demonstrate experimentally the feasibility of the predicted effect.

physics.optics↗

arXiv2010

Polychromatic nanofocusing of surface plasmon polaritons

We introduce the concept of polychromatic plasmonics and suggest an broadband plasmonic lens for nanofocusing of surface plasmon polaritons. The lens employs a parabolically modulated metal-dielectric-metal structure. This plasmonic lens has a bandwidth of more than an optical octave thus opening new opportunities for broadband plasmonic applications.

physics.optics↗

arXiv2010

Effects of polarization on the transmission and localization of classical waves in weakly scattering metamaterials

We summarize the results of our comprehensive analytical and numerical studies of the effects of polarization on the Anderson localization of classical waves in one-dimensional random stacks. We consider homogeneous stacks composed entirely of normal materials or metamaterials, and also mixed stacks composed of alternating layers of a normal material and metamaterial. We extend the theoretical study developed earlier for the case of normal incidence [A. A. Asatryan et al, Phys. Rev. B 81, 075124 (2010)] to the case of off-axis incidence. For the general case where both the refractive indices and layer thicknesses are random, we obtain the long-wave and short-wave asymptotics of the localization length over a wide range of incidence angles (including the Brewster ``anomaly'' angle). At the Brewster angle, we show that the long-wave localization length is proportional to the square of the wavelength, as for the case of normal incidence, but with a proportionality coefficient substantially larger than that for normal incidence. In mixed stacks with only refractive-index disorder, we demonstrate that p-polarized waves are strongly localized, while for s-polarization the localization is substantially suppressed, as in the case of normal incidence. In the case of only thickness disorder, we study also the transition from localization to delocalization at the Brewster angle.

cond-mat.dis-nn↗