arXiv subjects

Ilya Shadrivov

Publications and source records attributed to Ilya Shadrivov.

13 recordsLinked to original sources

arXiv2026

Amplified up-conversion of electromagnetic waves using time-varying metasurfaces

Time-varying metamaterials and photonic time crystals offer a powerful route to wave amplification through temporal modulation of material parameters. Here, we experimentally demonstrate amplified up-conversion of free-space electromagnetic waves in the microwave regime using a time-varying metasurface composed of varactor-loaded coupled split-ring resonators. The metasurface supports a cascaded parametric process in which temporal modulation enhances the resonant response near the signal frequency and subsequently enables efficient radiation at higher sum-frequency components. Direct measurements in degenerate and non-degenerate regimes show amplified up-conversion exceeding the single-step conversion estimate based on the Manley-Rowe frequency ratio. These results establish time-varying metasurfaces as an efficient platform for amplification, generation, and frequency conversion of electromagnetic waves in the microwave and terahertz bands, with potential extension to higher frequencies using ultrafast modulation mechanisms.

physics.optics↗

arXiv2026

Fundamental Limitations of Terahertz Quarter-Wave Plates Based on High-Contrast Dielectric Gratings

We present a systematic study of high-contrast dielectric gratings operating as broadband quarter-wave plates in the terahertz range. Using higher-order effective medium theory, we identify an achromatic operating regime characterized by a parabolic-like frequency dependence of the phase retardation. This framework reveals a fundamental bandwidth limit imposed by single-mode operation in one-dimensional rectangular gratings. We show that Fabry-Perot resonances and the higher-order modes set intrinsic constraints on achievable performance. The theoretical predictions are quantitatively validated by rigorous full-wave simulations and terahertz time-domain spectroscopy experiments. Our results reveal clear physical design rules and intrinsic performance limits for broadband terahertz dielectric grating waveplates.

physics.optics↗

arXiv2026

Multiresonant Membrane Metasurfaces for Multifunctional Fingerprint Recognition and Real-time Biochemical Tracking

Label-free identification and real-time tracking of biochemical substances became critical for molecular diagnostics and chemical analysis, yet conventional resonant terahertz metasurface sensing relies on a single resonance, limiting spectral selectivity and dynamic capability. Here, we suggest multiresonant membrane metasurfaces and implement them for simultaneous static molecular fingerprint retrieval and dynamic reaction monitoring within a single pixel. We consider a membrane metasurface supporting multiple quasi-bound states in the continuum designed at target frequencies and enabling the tailoring of the field enhancement and frequency-selective interaction with target analytes. As a proof-of-concept, we achieve label-free detection of the dual fingerprint absorption features of pefloxacin at 0.78 THz and 0.99 THz, and real-time tracking of vitamin C oxidation and denaturation under ambient conditions. The kinetic profiles extracted from the THz amplitude evolution show excellent agreement with nonlinear reaction models, demonstrating quantitative biochemical tracking capabilities. Our results establish a versatile and scalable THz photonic platform that unifies static fingerprint identification and dynamic reaction monitoring, paving the way toward integrated on-chip biochemical analytics and multifunctional metasurface sensors.

physics.optics↗

arXiv2025

Tunable bound states in the continuum through hybridization of 1D and 2D metasurfaces

This work presents a novel approach to create and dynamically control quasi-Bound States in the Continuum (BIC) resonances through the hybridization of 1D and 2D metasurfaces using micro-electromechanical systems (MEMS). By introducing out-of-plane symmetry breaking through a silicon MEMS membrane positioned above a 1D silicon metasurface, the quasi-BIC resonance's central wavelength and quality factor are precisely tuned. The proposed design achieves ultranarrow resonance linewidths with the spectral tuning range exceeding 60 nm while maintaining a constant quality factor. This tuning capability, realized through both horizontal displacement within a 1D metasurface and vertical MEMS membrane movement, offers a new degree of freedom for manipulating quasi-BIC resonances. The proposed hybridization of 2D and 1D metasurfaces using MEMS mechanism provides a practical route to dynamic modulation of transmission resonance characteristics, making it a promising candidate for tunable filters, spectroscopy, imaging, and sensing applications.

physics.optics↗

arXiv2024

Multiple Bound States in the Continuum: Towards Intense Terahertz Matter Interaction

Bound states in the continuum (BICs) are an excellent platform enabling highly efficient light-matter interaction in applications for lasing, nonlinear generation, and sensing. However, the current focus in implementing BICs has primarily been on single sharp resonances, limiting the extent of electric field enhancement for multiple resonances. In this study, we conducted experimental demonstrations to showcase how metasurfaces can enable the control of symmetry-broken and Friedrich-Wintgen BICs by leveraging the asymmetry of split resonant rings. This approach allows for the existence of multiple free-control BIC resonances and tailored enhancement of controlling light-matter interactions. We have conducted further experiments to validate the effectiveness and performance of our approach for identification of the distinct fingerprint of α-lactose with high sensitivity using only one single metasurface. These findings present a novel and efficient platform for the development of miniaturized and chip-scale photonics devices with intense light-matter interaction.

physics.optics↗

arXiv2023

High harmonic generation from a subwavelength dielectric resonator

Higher-order optical harmonics entered the realm of nanostructured solids being observed recently in optical gratings and metasurfaces with a subwavelength thickness. Structuring materials at the subwavelength scale allows for resonant enhancing of the efficiency of nonlinear processes and reducing the size of high-harmonic sources. Here we report the observation of up to a seventh harmonic generated from a single subwavelength resonator made of AlGaAs material. This process is enabled by careful engineering of the resonator geometry for supporting optical modes associated with a quasi-bound state in the continuum in the mid-infrared spectral range at around λ=3.7 μm pump wavelength. The resonator volume measures ~ 0.1 λ^3. The resonant modes are excited with an azimuthally polarized tightly focused beam. We evaluate the contributions of perturbative and non-perturbative nonlinearities to the harmonic generation process. Our work proves the possibility to miniaturize solid-state sources of high harmonics to the subwavelength volumes.

physics.optics↗

arXiv2022

Control of NV center radiation in nanodiamonds by silicon nanoantennas

The development of nanophotonics systems for the manipulation of the luminescent properties of single quantum emitters is essential for quantum communication and computing. Dielectric nanosystems enable various opportunities for light control through inherent electric and magnetic resonances, however their full potential has not yet been discovered. Here, the emission properties of NV centers in nanodiamonds placed in the near-field zone of silicon nanoresonators are investigated. It is demonstrated experimentally that the spontaneous emission rate of single NV centers in 50 nm nanodiamonds can be modified by their coupling to spherical nanoantennas, reducing the mode of the lifetime distribution by approximately 2 times from 16 ns to 9 ns. It is also shown that the collected intensity of photoluminescence emission from the multiple NV centers in 150 nm nanodiamond coupled to a cylindrical nanoantenna is increased by more than 50% compared to the intensity from the same nanodiamond on a bare substrate

physics.optics↗

arXiv2022

Topological membrane devices for terahertz on-chip photonics

Terahertz waves offer a profound platform for next-generation sensing, imaging, and information communications. However, all conventional terahertz components and systems suffer from a bulky design, sensitivity to imperfections, and transmission losses. Here, we propose and experimentally demonstrate on-chip integration and miniaturization of topological devices which may address many existing drawbacks of the terahertz technology. We design and fabricate topological devices based on valley-Hall photonic structures that can be employed for various integrated components of on-chip terahertz systems. More specifically, we demonstrate the valley-locked asymmetric energy flow and mode conversion with topological straight waveguide, multi-port couplers, wave division, and whispering gallery mode resonators. Our devices are based on topological membrane metasurfaces which are of great importance for developing on-chip photonics and bringing many novel features into terahertz devices.

physics.optics↗

arXiv2014

Multilayer graphene waveguides

We study dispersion properties of TM-polarized electromagnetic waves guided by a multilayer graphene metamaterial. We demonstrate that both dispersion and localization of the guided modes can be efficiently controlled by changing the number of layers in the structure. Remarkably, we find that in the long wavelength limit, the dispersion of the fundamental mode of the N-layer graphene structure coincides with the dispersion of a plasmon mode supported by a single graphene layer, but with N times larger conductivity. We also compare our exact dispersion relations with the results provided by the effective media model.

physics.optics↗

arXiv2012

Novel hyperbolic metamaterials based on multilayer graphene structures

We suggest a new class of hyperbolic metamaterials for THz frequencies based on multilayer graphene structures. We calculate the dielectric permittivity tensor of the effective nonlocal medium with a periodic stack of graphene layers and demonstrate that tuning from elliptic to hyperbolic dispersion can be achieved with an external gate voltage. We reveal that such graphene structures can demonstrate a giant Purcell effect that can be used for boosting the THz emission in semiconductor devices. Tunability of these structures can be enhanced further with an external magnetic field which leads to the unconventional hybridization of the TE and TM polarized waves.

cond-mat.mes-hall↗

arXiv2012

Tunable hybrid surface waves supported by a graphene layer

We study surface waves localized near a surface of a semi-infinite dielectric medium covered by a layer of graphene in the presence of a strong external magnetic field. We demonstrate that both TE-TM hybrid surface plasmons can propagate along the graphene surface. We analyze the effect of the Hall conductivity on the disper- sion of hybrid surface waves and suggest a possibility to tune the plasmon dispersion by the magnetic field.

physics.optics↗

arXiv2009

Structural tunability in metamaterials

We propose a novel approach for efficient tuning of the transmission characteristics of metamaterials through a continuous adjustment of the lattice structure, and confirm it experimentally in the microwave range. The concept is rather general and applicable to various metamaterials as long as the effective medium description is valid. The demonstrated continuous tuning of metamaterial response is highly desirable for a number of emerging applications of metamaterials including sensors, filters, switches, realizable in a wide frequency range.

physics.optics↗

arXiv2002

Interaction of vector solitons with a nonlinear interface

We develop the analytical method of field momenta for analyzing the dynamics of optical vector solitons in photorefractive nonlinear media. First, we derive the effective evolution equations for the parameters of multi-component solitons composed of incoherently coupled beams and investigate the soliton internal oscillations associated with the relative motion of the soliton components. Then, we apply this method for analyzing the vector soliton scattering by a nonlinear interface. In particular, we show that a vector soliton can be reflected, transmitted, captured, or split into separate components, depending on the initial energy of its internal degree of freedom. The results are verified by direct numerical simulations of spatial optical solitons in photorefractive nonlinear media.

nlin.PS↗