arXiv subjects

Arseniy I. Kuznetsov

Publications and source records attributed to Arseniy I. Kuznetsov.

At least 37 records · Page 2Linked to original sources

arXiv2020

Generation of even and odd high harmonics in resonant metasurfaces using single and multiple ultra-intense laser pulses

High harmonic generation (HHG) opens a window on the fundamental science of strong-field light-mater interaction and serves as a key building block for attosecond optics and metrology. Resonantly enhanced HHG from hot spots in nanostructures is an attractive route to overcoming the well-known limitations of gases and bulk solids. We demonstrate a nanoscale platform for highly efficient HHG driven by strong mid-infrared laser pulses: an ultra-thin resonant gallium phosphide (GaP) metasurface. The wide bandgap and the lack of inversion symmetry of the GaP crystal enable the generation of even and odd harmonics covering a wide range of photon energies between 1.3 and 3 eV with minimal reabsorption. The resonantly enhanced conversion efficiency facilitates single-shot measurements that avoid material damage and pave the way to controllable transition between perturbative and non-perturbative regimes of light-matter interactions at the nanoscale.

physics.optics↗

arXiv2020

Large-scale Huygens metasurfaces for holographic 3D near-eye displays

Novel display technologies aim at providing the users with increasingly immersive experiences. In this regard, it is a long-sought dream to generate three-dimensional (3D) scenes with high resolution and continuous depth, which can be overlaid with the real world. Current attempts to do so, however, fail in providing either truly 3D information, or a large viewing area and angle, strongly limiting the user immersion. Here, we report a proof-of-concept solution for this problem, and realize a compact holographic 3D near-eye display with a large exit pupil of 10mm x 8.66mm. The 3D image is generated from a highly transparent Huygens metasurface hologram with large (>10^8) pixel count and subwavelength pixels, fabricated via deep-ultraviolet immersion photolithography on 300 mm glass wafers. We experimentally demonstrate high quality virtual 3D scenes with ~50k active data points and continuous depth ranging from 0.5m to 2m, overlaid with the real world and easily viewed by naked eye. To do so, we introduce a new design method for holographic near-eye displays that, inherently, is able to provide both parallax and accommodation cues, fundamentally solving the vergence-accommodation conflict that exists in current commercial 3D displays.

physics.optics↗

arXiv2020

Nonlinear interferometry with infrared metasurfaces

The optical elements comprised of sub-diffractive light scatterers, or metasurfaces, hold a promise to reduce the footprint and unfold new functionalities of optical devices. A particular interest is focused on metasurfaces for manipulation of phase and amplitude of light beams. Characterisation of metasurfaces can be performed using interferometry, which, however, may be cumbersome, specifically in the infrared (IR) range. Here, we realise a new method for characterising IR metasurfaces based on nonlinear interference, which uses accessible components for visible light. Correlated IR and visible photons are launched into a nonlinear interferometer so that the phase profile, imposed by the metasurface on the IR photons, modifies the interference at the visible photon wavelength. Furthermore, we show that this concept can be used for broadband manipulation of the intensity profile of a visible beam using a single IR metasurface. Our method unfolds the potential of quantum interferometry for the characterization of advanced optical elements.

physics.optics↗

arXiv2020

Demonstration of second harmonic generationin gallium phosphide nano-waveguides

We designed, fabricated and tested gallium phosphide (GaP) nano-waveguides for second harmonic generation (SHG). We demonstrate SHG in the visible range around 655 nm using low power continuous-wave pump in the optical communication O-band. Our structures utilize modal phase matching, such that lower order eigenmodes of the pump are phase matched to higher order eigenmodes of the second harmonic. We observe phase matched SHG for different combinations of interacting modes by varying the widths of the waveguides and tuning the wavelength of the pump. The presented results contribute to the development of integrated photonic platforms with efficient nonlinear wave-mixing processes for classical and quantum applications.

physics.optics↗

arXiv2020

Lasing action in single subwavelength particles supporting supercavity modes

On-chip light sources are critical for the realization of fully integrated photonic circuitry. So far, semiconductor miniaturized lasers have been mainly limited to sizes on the order of a few microns. Further reduction of sizes is challenging fundamentally due to the associated radiative losses. While using plasmonic metals helps to reduce radiative losses and sizes, they also introduce Ohmic losses hindering real improvements. In this work, we show that, making use of quasi-bound states in the continuum, or supercavity modes, we circumvent these fundamental issues and realize the smallest purely semiconductor nanolaser thus far. Here, the nanolaser structure is based on a single semiconductor nanocylinder that intentionally takes advantage of the destructive interference between two supported optical modes, namely Fabry-Perot and Mie modes, to obtain a significant enhancement in the quality factor of the cavity. We experimentally demonstrate the concept and obtain optically pumped lasing action using GaAs at cryogenic temperatures. The optimal nanocylinder size is as small as 500 nm in diameter and only 330 nm in height with a lasing wavelength around 825 nm, corresponding to a size-to-wavelength ratio around 0.6. The obtained results pave the way for the development of smaller on-chip light sources free of Ohmic losses, which may find applications in the future photonic circuits.

physics.optics↗

arXiv2019

Control of LED Emission with Functional Dielectric Metasurfaces

The improvement of light-emitting diodes (LEDs) is one of the major goals of optoelectronics and photonics research. While emission rate enhancement is certainly one of the targets, in this regard, for LED integration to complex photonic devices, one would require to have, additionally, precise control of the wavefront of the emitted light. Metasurfaces are spatial arrangements of engineered scatters that may enable this light manipulation capability with unprecedented resolution. Most of these devices, however, are only able to function properly under irradiation of light with a large spatial coherence, typically normally incident lasers. LEDs, on the other hand, have angularly broad, Lambertian-like emission patterns characterized by a low spatial coherence, which makes the integration of metasurface devices on LED architectures extremely challenging. A novel concept for metasurface integration on LED is proposed, using a cavity to increase the LED spatial coherence through an angular collimation. Due to the resonant character of the cavity, extending the spatial coherence of the emitted light does not come at the price of any reduction in the total emitted power. The experimental demonstration of the proposed concept is implemented on a GaP LED architecture including a hybrid metallic-Bragg cavity. By integrating a silicon metasurface on top we demonstrate two different functionalities of these compact devices: directional LED emission at a desired angle and LED emission of a vortex beam with an orbital angular momentum. The presented concept is general, being applicable to other incoherent light sources and enabling metasurfaces designed for plane waves to work with incoherent light emitters.

physics.optics↗

arXiv2019

Phase-only transmissive spatial light modulator based on tunable dielectric metasurface

Rapidly developing augmented reality (AR) and 3D holographic display technologies require spatial light modulators (SLM) with high resolution and viewing angle to be able to satisfy increasing customer demands. Currently available SLMs, as well as their performance, are limited by their large pixel sizes of the order of several micrometres. Further pixel size miniaturization has been stagnant due to the persistent challenge to reduce the inter-pixel crosstalk associated with the liquid crystal (LC) cell thickness, which has to be large enough to accumulate the required 2π phase difference. Here, we propose a concept of tunable dielectric metasurfaces modulated by a liquid crystal environment, which can provide abrupt phase change and uncouple the phase accumulation from the LC cell thickness, ultimately enabling the pixel size miniaturization. We present a proof-of-concept metasurface-based SLM device, configured to generate active beam steering with >35% efficiency and large beam deflection angle of 11°, with LC cell thickness of only 1.5 μm, much smaller than conventional devices. We achieve the pixel size of 1.14 μm corresponding to the image resolution of 877 lp/mm, which is 30 times larger comparing to the presently available commercial SLM devices. High resolution and viewing angle of the metasurface-based SLMs opens up a new path to the next generation of near-eye AR and 3D holographic display technologies.

physics.optics↗

arXiv2018

Lasing action in active dielectric nanoantenna arrays

Directional lasing, with a low threshold and high quality factor, in active dielectric nanoantenna arrays is demonstrated. This is achieved through a leaky resonance excited in coupled gallium arsenide (GaAs) nanopillars. The leaky resonance is formed by partially breaking a bound state in the continuum (BIC) generated by the collective, vertical electric dipole resonances excited in the nanopillars for sub-diffractive arrays. By opening an unprotected, diffractive channel along one of the periods of the array one can control the directionality of the emitted light without sacrificing the high Q associated with the BIC mode, thus achieving directional lasing. A quality factor Q = 2750 is achieved at a controlled angle of emission of ~ 3 degrees with respect to the normal of the array with a pumping fluence as low as 10 uJ/cm^2. We demonstrate the possibility to control the lasing directivity and wavelength by changing the geometrical parameters of the nanoantenna array, and by tuning the gain spectrum of GaAs with temperature. Lasing action is demonstrated at different wavelengths and emission at different angles, which can be as large as 25 degrees to the normal. The obtained results provide guidelines for achieving surface emitting laser devices based on active dielectric nanoantennas that are compact and highly transparent.

physics.optics↗

arXiv2018

A Metalens with Near-Unity Numerical Aperture

The numerical aperture (NA) of a lens determines its ability to focus light and its resolving capability. Having a large NA is a very desirable quality for applications requiring small light-matter interaction volumes or large angular collections. Traditionally, a large NA lens based on light refraction requires precision bulk optics that ends up being expensive and is thus also a specialty item. In contrast, metasurfaces allow the lens designer to circumvent those issues producing high NA lenses in an ultra-flat fashion. However, so far, these have been limited to numerical apertures on the same order of traditional optical components, with experimentally reported values of NA <0.9. Here we demonstrate, both numerically and experimentally, a new approach that results in a diffraction limited flat lens with a near-unity numerical aperture (NA>0.99) and sub-wavelength thickness (~λ/3), operating with unpolarized light at 715 nm. To demonstrate its imaging capability, the designed lens is applied in a confocal configuration to map color centers in sub-diffractive diamond nanocrystals. This work, based on diffractive elements able to efficiently bend light at angles as large as 82°, represents a step beyond traditional optical elements and existing flat optics, circumventing the efficiency drop associated to the standard, phase mapping approach.

physics.optics↗

arXiv2016

Time-resolved spectroscopy with entangled photons

Interaction of light with media often occurs with a femtosecond response time. Its measurement by conventional techniques requires the use of femtosecond lasers and sophisticated time-gated optical detection1-3. Here we demonstrate that by exploiting quantum interference of entangled photons it is possible to measure the phase relaxation time of a media on the femtosecond time scale (down to 100 fs) using accessible continuous wave laser and single-photon counting. We insert the sample in the Hong-Ou-Mandel interferometer4 and infer the phase relaxation time from the modification of the two-photon interference pattern. In addition to its simplicity and ease of use, the technique does not require compensation of group velocity dispersion5-8 and does not induce photo-damage of the samples. This technique will be useful for characterization of ultrafast phase relaxation processes in material science, chemistry, and biology.

quant-ph↗

arXiv2016

Suppression of scattering for small dielectric particles: an anapole mode and invisibility

We reveal that an isotropic homogeneous subwavelength particle with a high refractive index can produce ultra-weak total scattering due to vanishing contribution of the electric dipole moment. This effect can be explained with the help of the Fano resonance and scattering efficiency associated with the excitation of an anapole mode. The latter is a nonradiative mode emerging from destructive interference of electric and toroidal dipole moments, and it can be employed for a design of highly transparent optical materials.

physics.optics↗

arXiv2015

Generalized Brewster-Kerker effect in dielectric metasurfaces

Polarization is one of the key properties defining the state of light. It was discovered in the early 19th century by Brewster, among others, while studying light reflected from materials at different angles. These studies led to the first polarizers, based on Brewster's effect. One of the most active trends in photonics now is devoted to the study of miniaturized, sub-wavelength devices exhibiting similar, or even improved, functionalities compared to those achieved with bulk optical elements. In the present work, it is theoretically predicted that a properly designed all-dielectric metasurface exhibits a generalized Brewster effect potentially for any angle, wavelength and polarization of choice. The effect is experimentally demonstrated for an array of silicon nanodisks at visible wavelengths. The underlying physics of this effect can be understood in terms of the suppressed scattering at certain angles that results from the interference between the electric and magnetic dipole resonances excited in the nanoparticles, predicted by Kerker in early 80s. This reveals deep connection of Kerker's and Brewster's legacies and opens doors for Brewster phenomenon to new applications in photonics, which are not bonded to a specific polarization or angle of incidence.

physics.optics↗

arXiv2014

Optimum Forward Light Scattering by Spherical and Spheroidal Dielectric Nanoparticles with High Refractive Index

High-refractive index dielectric nanoparticles may exhibit strong directional forward light scattering at visible and near-infrared wavelengths due to interference of simultaneously excited electric and magnetic dipole resonances. For a spherical high-index dielectric, the so-called first Kerker's condition can be realized, at which the backward scattering practically vanishes for some combination of refractive index and particle size. However, Kerker's condition for spherical particles is only possible at the tail of the scattering resonances, when the particle scatters light weakly. Here we demonstrate that significantly higher forward scattering can be realized if spheroidal particles are considered instead. For each value of refractive index exists an optimum shape of the particle, which produces minimum backscattering efficiency together with maximum forward scattering. This effect is achieved due to the overlapping of magnetic and electric dipole resonances of the spheroidal particle at the resonance frequency. It permits the design of very efficient, low-loss optical nanoantennas.

physics.optics↗

arXiv2014

Seeing the unseen: observation of an anapole with dielectric nanoparticles

Nonradiating current configurations attract attention of physicists for many years as possible models of stable atoms in the field theories. One intriguing example of such a nonradiating source is known as anapole (which means without poles in Greek), and it was originally proposed by Yakov Zeldovich in nuclear physics. Recently, an anapole was suggested as a model of elementary particles describing dark matter in the Universe. Classically, an anapole mode can be viewed as a composition of electric and toroidal dipole moments, resulting in destructive interference of the radiation fields due to similarity of their far-field scattering patterns. Here we demonstrate experimentally that dielectric nanoparticles can exhibit a radiationless anapole mode in visible. We achieve the spectral overlap of the toroidal and electric dipole modes through a geometry tuning, and observe a highly pronounced dip in the far-field scattering accompanied by the specific near-field distribution associated with the anapole mode. The anapole physics provides a unique playground for the study of electromagnetic properties of nontrivial excitations of complex fields, reciprocity violation, and Aharonov-Bohm like phenomena at optical frequencies.

physics.optics↗

arXiv2014

All-dielectric optical nanoantennas (Review)

We propose a new type of highly efficient Yagi-Uda nanoantenna and introduced a novel concept of superdirective nanoantennas based on silicon nanoparticles. In addition to the electric response, this silicon nanoantennas exhibit very strong magnetic resonances at the nanoscale. Both types of nanoantennas are studied analytically, numerically and experimentally. For superdirective nanoantennas we also predict the effect of the beam steering at the nanoscale characterized by a subwavelength sensitivity of the beam radiation direction to the source position.

physics.optics↗

arXiv2014

Quantum spectroscopy of plasmonic nanostructures

We use frequency entangled photons, generated via spontaneous parametric down conversion, to measure the broadband spectral response of an array of gold nanoparticles exhibiting Fano-type plasmon resonance. Refractive index sensing of a liquid is performed by measuring the shift of the array resonance. This method is robust in excessively noisy conditions compared with conventional broadband transmission spectroscopy. Detection of a refractive index change is demonstrated with a noise level 70 times higher than the signal, which is shown to be inaccessible with the conventional transmission spectroscopy. Use of low photon fluxes makes this method suitable for measurements of photosensitive bio-samples and chemical substances.

quant-ph↗

arXiv2013

Split-ball resonator

We introduce a new concept of split-ball resonator and demonstrate a strong magnetic dipole response for both gold and silver spherical plasmonic nanoparticles with nanometer-scale cuts. Tunability of the magnetic dipole resonance throughout the visible spectral range is demonstrated by changing the depth and width of the nanoscale cut. We realize this novel concept experimentally by employing the laser-induced transfer method to produce near-perfect spheres and helium ion beam milling to make cuts with the nanometer resolution. Due to high quality of the spherical particle shape governed by strong surface tension forces during the laser transfer process and clean, straight side walls of the cut made by helium ion milling, the magnetic resonance is observed at 600 nm in gold and at 565 nm in silver nanoparticles. Structuring arbitrary features on the surface of nanoscale spherical resonators provides new ways for engineering hybrid resonant modes and ultra-high near-field enhancement.

physics.optics↗

arXiv2012

Directional visible light scattering by silicon nanoparticles

Directional light scattering by spherical silicon nanoparticles in the visible spectral range is experimentally demonstrated for the first time. These unique scattering properties arise due to simultaneous excitation and mutual interference of magnetic and electric dipole resonances inside a single nanosphere. Directivity of the far-field radiation pattern can be controlled by changing light wavelength and the nanoparticle size. Forward-to-backward scattering ratio above 6 can be experimentally obtained at visible wavelengths. These unique properties of silicon nanoparticles make them promising for design of novel low-loss visible- and telecom-range nanoantenna devices.

physics.optics↗