bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of different sized nanoparticles combined with ultrasound on the optical properties of in vitro knee joint and knee osteoarthritis cartilage tissue was studied by OCT and diffuse reflectance spectroscopy
Authors: An Ran , Wei Huajiang , Zhuang Ze , Guo Zhouyi , He Yonghong , Xie Shusen , Yang Hongqin , Gu Huaimin
Published: November 2021

The penetration and accumulation of zinc oxide nanoparticles (ZnO NPs) with different sizes in human normal knee joint (NKJ) tissue and knee osteoarthritis (OA) tissue were studied by continuous optical coherence tomography and diffuse reflectance (DR) spectroscopy in this paper, and the effects of ZnO NPs of two sizes (30 nm and 90 nm) and ultrasound (US) on the optical properties of human NKJ and OA tissue were evaluated. The results show that the average attenuation coefficients of NKJ tissue decrease by 14.90%, 26.91%, 33.52% and 37.01%, and the DR spectra increases by 8.444%, 12.901%, 18.219% and 26.125%, respectively, after being treated with 90 nm ZnO NPs, 90 nm ZnO NPs/US, 30 nm ZnO NPs and 30 nm ZnO NPs/US. The average attenuation coefficients of OA tissue are reduced by 32.14%, 49.51%, 57.85% and 72.30%, and the DR spectra increase by 17.426%, 23.116%, 25.218% and 29.326%, respectively, after being treated with 90 nm ZnO NPs, 90 nm ZnO NPs/US, 30 nm ZnO NPs and 30 nm ZnO NPs/US. It is concluded that the optical properties of NKJ and OA tissues are greatly influenced by ZnO NPs and US. Nanoparticles have a greater impact on OA tissue than on NKJ tissue.
Noncollinear phase-matching geometries in ultra-broadband quasi-parametric amplification
Authors: Wang Ji , Zheng Yanqing , Chen Yunlin
Published: November 2021

Optical parametric chirped pulse amplification (OPCPA) shows great potential in producing ultrashort high-intensity pulses because of its large gain bandwidth. Quasi-parametric chirped pulse amplification (QPCPA) may further extend the bandwidth. However, behavior of QPCPA at a limited pump intensity (e.g., ≤ 5 GW/cm2 in a nanosecond pumped QPCPA) has not yet been investigated fully. We discuss detailedly the ultra-broadband amplification and the noncollinear phase-matching geometry in QPCPA, model and develop a novel noncollinear geometry in QPCPA, namely triple-wavelength phase-matching geometry, which provides two additional phase-matching points around the phase-matching point at the central wavelength. Our analysis demonstrates that the triple-wavelength phase-matching geometry can support stable, ultra-broadband amplification in QPCPA. The numerical simulation results show that ultrashort pulse with a pulse duration of 7.92 fs can be achieved in QPCPA when the pump intensity is limited to 5 GW/cm2, calculated using the nonlinear coefficient of YCa4O(BO3)3.
Energy spreading, equipartition, and chaos in lattices with non-central forces
Authors: Ngapasare Arnold , Theocharis Georgios , Richoux Olivier , Achilleos Vassos , Skokos Charalampos
Published: November 2021

We numerically study a one-dimensional, nonlinear lattice model which in the linear limit is relevant to the study of bending (flexural) waves. In contrast with the classic one-dimensional mass-spring system, the linear dispersion relation of the considered model has different characteristics in the low frequency limit. By introducing disorder in the masses of the lattice particles, we investigate how different nonlinearities in the potential (cubic, quadratic, and their combination) lead to energy delocalization, equipartition, and chaotic dynamics. We excite the lattice using single site initial momentum excitations corresponding to a strongly localized linear mode and increase the initial energy of excitation. Beyond a certain energy threshold, when the cubic nonlinearity is present, the system is found to reach energy equipartition and total delocalization. On the other hand, when only the quartic nonlinearity is activated, the system remains localized and away from equipartition at least for the energies and evolution times considered here. However, for large enough energies for all types of nonlinearities we observe chaos. This chaotic behavior is combined with energy delocalization when cubic nonlinearities are present, while the appearance of only quadratic nonlinearity leads to energy localization. Our results reveal a rich dynamical behavior and show differences with the relevant Fermi–Pasta–Ulam–Tsingou model. Our findings pave the way for the study of models relevant to bending (flexural) waves in the presence of nonlinearity and disorder, anticipating different energy transport behaviors.
Structure design for high performance n-type polymer thermoelectric materials
Authors: Zhang Qi , Sun Hengda , Zhu Meifang
Published: November 2021

Organic thermoelectric (OTE) materials have been regarded as a potential candidate to harvest waste heat from complex, low temperature surfaces of objects and convert it into electricity. Recently, n-type conjugated polymers as organic thermoelectric materials have aroused intensive research in order to improve their performance to match up with their p-type counterpart. In this review, we discuss aspects that affect the performance of n-type OTEs, and further focus on the effect of planarity of backbone on the doping efficiency and eventually the TE performance. We then summarize strategies such as implementing rigid n-type polymer backbone or modifying conventional polymer building blocks for more planar conformation. In the outlook part, we conclude forementioned devotions and point out new possibility that may promote the future development of this field.
A Stellar Ranging Scheme Based on the Second-order Correlation Measurement
Authors: Li Jian , Xu Can , Liu Yinshen , Ma Yaqi , Liu Xinyao , Ma Xiaochen , Fan Run , Zhang An-Ning
Published: November 2021

Stellar ranging is the basis for stellar dynamics research and in-depth research on astrophysics. The parallax method is the most widely used and important basic method for stellar ranging. However, it needs to perform high-precision measurement of the parallax angle and the baseline length together. We aim to propose a new stellar ranging scheme based on second-order correlation that does not require a parallax angle measurement. We hope our solution can be as basic as the parallax method. We propose a new stellar ranging scheme by using the offset of second-order correlation curve signals. The optical path difference between the stars and different base stations is determined by the offset of the second-order correlation curve signals. Then the distance of the stars could be determined by the geometric relation. With the distance to stars out to 10 kpc away, our astrometric precision can be better compared to Gaia by simulation. We also design an experiment and successfully demonstrate the feasibility of this scheme. This stellar ranging scheme enables further and more accurate stellar ranging without requiring any prior information or angle measurement.
Realisation of the ITS-90 and thermodynamic temperature measurements above 960 °C using a monochromator-based radiance comparator
Authors: Bourson F , Briaudeau S , Sadli M , Rougié B , Kozlova O
Published: November 2021

At LNE-Cnam, the international temperature scale of 1990 (ITS-90) and thermodynamic temperature measurements above the silver point, are carried out with a radiance comparator. This instrument is, more generally, devoted to any radiance comparison in temperature range from the ambient to 3000 °C. The instrument developed in the early 1990s at LNE-Cnam has the advantage of being completely adjustable. Compared to compact radiation thermometers based on lenses and a narrow-band interference filter, the radiance comparator is only made of gold coated mirrors and a Czerny–Turner monochromator to select the spectral bandwidth. The instrument offers the possibility to tune the geometric extent and the slit scattering function. In return, the radiance comparator is a complex instrument that requires a complete and a regular characterisation at the highest level of accuracy. In the first part, this paper describes the instrument and its operating principle. In a second part, a complete study of the wavelength calibration, the slit scattering function, size of source effect, out-of-band transmittance, linearity and other main sources of uncertainty are presented and discussed. Their associated uncertainties are estimated separately and are grouped together to give an example of propagation of uncertainties when realising the ITS-90.
Numerical simulation of wave propagation and plasma response excited in field-reversed configuration plasma
Authors: Urano Takahiro , Takahashi Toshiki , Asai Tomohiko , Okada Shigefumi
Published: November 2021

A hybrid simulation (a model that treats ions as particles and electrons as fluid) is performed to analyse the propagation of waves excited in the field-reversed configuration plasma and the resulting plasma response. The current of the wave excitation antenna changes in a sine wave, and its frequency is set so that it has an ion cyclotron resonance point inside the separatrix. When the antenna current is maximum, a magnetic field with a magnitude of 40% of the external magnetic field is created on the separatrix. A toroidal magnetic field is excited in the plasma by applying waves. The observed propagation velocity of the toroidal magnetic field is comparable with the shear Alfvén wave outside the separatrix, and is on the same order within the separatrix. This result has a tendency similar to the propagation velocity outside the separatrix reported in the wave experiment in the past FIX machine. The simulation results also show that when the excited magnetic field propagates in the axial direction, the separatrix is compressed or expanded, and the high-density region of the ions formed thereby moves in the axial direction. In addition, the excited magnetic energy is rapidly decreased near the position where the velocities of the shear Alfvén wave and the ion sound wave are equal (local beta value is 0.88). It is found that the decay of the excited magnetic energy occurred at a point outside the ion cyclotron resonance point. This suggests that the compression and expansion of the plasma is caused while maintaining the quasi-equilibrium state according to the change in the external magnetic pressure.
Investigation of directivity of the nanoantenna by its inherent resonant states
Authors: Agrahari Rajan , Shamkhi Hadi K.
Published: November 2021

We present a quasinormal mode (QNM) approach for modeling the nanoantenna and describe the response of localized dielectric cylinder resonators. The inherent resonant states of the dielectric cylinder nanocavity are investigated for modified and reduced geometrical symmetry. We find some modes contributing mainly to the directivity and have a high-quality factor. The variation of the eigenmodes with cylinder height and substrate refractive index has also been investigated.
Highly Directive All-Dielectric Nanoantenna
Authors: Agrahari Rajan , Shamkhi Hadi K.
Published: November 2021

A highly directive dielectric nanoantenna in an integrated chip may enable faster communication as their low losses and small size overcome the limitation of temperature enhancement and low data transfer rate. We optimize nanoantenna consist of Si-nanoblock in the near-infrared region to efficiently transfer a point dipole light to a highly directive light in the far-field region. We engineer the intrinsic electric and magnetic resonances of a Si-block nanoantenna by modifying and reducing its geometrical symmetry. We realize a pronounced enhancement of directivity by systematically inducing perturbation in the Silicon block so that both its reflection and rotational symmetries are broken. Finally, we retain the traditional method to increase resonance’s coupling to outer space by introducing substrate with an increasing refractive index. We find that the directivity has boosted rapidly.
Wide-angle Reconfigurable Refraction by Silicon Fourier Metasurfaces
Authors: Antonov A A , Gorkunov M V
Published: November 2021

We design metasurfaces based on silicon films with smooth relief described by several Fourier harmonics and study their ability to redirect the refracted light over a wide angular range controlled by subtle variations of the optical setup. We use semi-analytical approach based on the Rayleigh hypothesis as well as full-scale numerical solutions to optimize the relief shape. To illustrate the reconfigurability potential, we design metasurfaces efficiently redirecting the refracted light from 83° to −73° with respect to the normal, when the angle of incidence is varied from 0° to 2°, and from 80° to −74°, when the substrate permittivity is altered from 2.3 to 2.2.
Effective electrodynamical parameters and microwave heating of radially heterogeneous pellets containing EAF dust and biochar
Authors: Anzulevich Anton P , Butko Leonid N , Pavlov Dmitry A , Kalganov Dmitry A , Tolkachev Valentin A , Anzulevich Svetlana N , Buchelnikov Vasiliy D , Moiseev Sergey G , Peng Zhiwei
Published: November 2021

In this work, we investigated the effect of microwave radiation with radially heterogeneous pellets consisting of electric arc furnace (EAF) dust and biochar. We reviewed the possible content of EAF dust in terms of permittivity and permeability of its components and calculated effective permittivity and permeability of EAF dust by an effective medium approach. Using obtained values we calculated dependencies of effective permittivity and permeability of EAF dust - biochar composite mixture on the volume fraction of EAF dust and conductivity of biochar. Taking into account these dependencies we simulated electromagnetic field and temperature distribution within pellet with a radial dependency of volume fraction of EAF dust and effective permittivity correspondingly.
ITO-free Perovskite Light-Emitting Electrochemical Cell
Authors: Baeva M , Gets D , Bodyago E , Mozharov A , Neplokh V , Nasibulin A , Mukhin I , Makarov S
Published: November 2021

Since Complementary metal–oxide–semiconductor technology is the conventional technology for micro- and optoelectronics, integration of emerging materials, such as halide perovskites, into the process is an important branch of perovskite technologies development. In this regard ITO free device research becomes increasingly important. The Perovskite Light-Emitting electrochemical cells are a promising alternative to conventional Perovskite Light Emitting Diodes. In this work we demonstrate green (λEL = 523 nm) CsPbBr3 Perovskite Light-Emitting electrochemical cells with luminescence intensity of 50 kd/m2 integrated with Si++(111) substrate.
High-Q two-groove resonator for all-dielectric Bloch surface wave platform
Authors: Bezus E A , Kadomina E A , Bykov D A , Morozov A A , Doskolovich L L
Published: November 2021

We propose a simple integrated resonant structure for the Bloch surface wave platform, which consists of two subwavelength grooves patterned on the surface of a one-dimensional dielectric photonic crystal. We demonstrate that the investigated structure can operate in a parasitic-scattering-free regime and, in this case, provide unity transmittance and zero reflectance at resonance conditions associated with the excitation of a leaky mode of the structure localized at the central ridge formed by the grooves. The proposed structure may find application in integrated photonic devices for optical filtering and analog optical computing.
Are there bound states in the continuum in a dielectric ring?
Authors: Bochek D V , Solodovchenko N S , Samusev K B , Limonov M F
Published: November 2021

Trapping and confining electromagnetic waves is important in both basic research and a variety of applications. For these purposes, various physical mechanisms are exploited including bound states in the continuum, which have been actively investigated recently. Bound states in the continuum have been observed in various objects consisting of both one and a number of dielectric structures. In particular, these photonic states were observed in high-contrast dielectric cylinders in the regime of strong eigenmode coupling, which leads to destructive interference in the far-field zone. In this article, we present the results of a study of bound states in a continuum in a dielectric ring, i.e. cylinder with coaxial air hole. The dependence of the quality factor Q on the normalized diameter of the hole is discussed.
Creation of an MRI phantom based on super-paramagnetic nanoparticles of iron oxide (SPIO) for standardization of the conversion of T2 * values in the concentration of iron in the liver
Authors: Bulanov P.A. , Nazarova E.E. , Menshchikov P.E. , Kupriyanov D.A , Tereshchenko G.V. , Novichkova G.A.
Published: November 2021

In this study the standardization method for T2* maps acquisition on various MR scanners (3T and 1.5T) is proposed. The reproducibility of the obtained T2* values is realized through the MR-compatible phantom containing paramagnetic complex iron oxide nanoparticles. The repeatability of measurements results has shown that the created phantom retains all the required characteristics (homogeneity, stability of concentrations and manifested paramagnetic properties) over a long period of time. The application of standardized T2* values allows to use previously received T2*, [ms] to iron concentrations in the dry substance of the liver (LIC), [mg/ml] conversion formulas for accurate, fast and non-invasive MRI diagnostics of liver iron overload.
Elastic Trapped Modes in Solid Acoustic Resonators of Various Shapes
Authors: Deriy Ilya , Toftul Ivan , Petrov Mihail , Bogdanov Andrey
Published: November 2021

Resonators are one of the main building blocks of many acoustic, photonic, and microwave devices such as metasurfaces, sensing devices, antennas, and many more. One of the main properties of any resonator, which also determines the properties of the structure, based on the resonator, is the quality (Q) factor. Q-factor of the resonator is limited due to material and radiative losses. In this paper, we propose the existence of modes of solid resonators, immersed in a nonviscious fluid, which are non-radiative, and therefore, their Q-factor is limited only by material losses.
Finding exceptional points in realistic systems using full-wave simulations
Authors: Dmitriev Alexey A , Rybin Mikhail V
Published: November 2021

Here, we present an approach to finding exceptional points using the finite-element method. Using this method, we demonstrated exceptional points in 2D dimers of infinite cylinders and infinite parallelepipeds. The results agree well with the analytical coupled-dipole model, however a deviation due to the contribution of higher multipoles, is present. Our approach can be applied to three-dimensional particles as well.
Cellular SERS structures for non-invasive study of living cells
Authors: Doroshina N V , Ushkov A A , Brazhe N A , Gorin D A , Mokrousov M D , Yakubovsky D I , Kapitanova O O , Voronov A A , Arsenin A V , Volkov V S , Novikov S M
Published: November 2021

Surface-enhanced Raman spectroscopy (SERS) is a potent and highly selective tool to chemically identify and determine the structure of molecules and materials. However, the large biomolecules and living cells are still difficult to study using modern SERS-substrates. Here we present a new approach to the geometry of the surface of plasmon nanostructures (cellular surfaces), which makes it possible to efficiently work with volumetric objects as cells or organelles. We use the scanning Raman microscope to map the SERS from the specially prepared microcapsules formed with a Layer-by-Layer deposition method and with built-in Raman tags (Indocyanine green). It demonstrated the possibility to detect SERS signal from Indocyanine green in microcapsules located in cavities, while the signal from the Raman dye in microcapsules located on a flat surface is not detected. The obtained results can be useful in biosensors applications.
Integrated high-contrast diffraction gratings for surface electromagnetic waves
Authors: Doskolovich L L , Bezus E A , Bykov D A
Published: November 2021

We propose and theoretically and numerically investigate integrated high-contrast diffraction gratings for surface electromagnetic waves. We consider two platforms for the on-chip gratings: surface plasmon-polaritons propagating along metal-dielectric interfaces and Bloch surface waves propagating along interfaces of photonic crystals. We demonstrate that the optical properties of the studied integrated gratings are qualitatively close to the ones of the conventional high-contrast diffraction gratings. If the “parasitic” out-of-plane scattering is suppressed, the reflectance and transmittance of the on-chip gratings are not only qualitatively, but also quantitatively close to the corresponding values of the conventional “free-space” gratings. The obtained results may find application in novel integrated optical circuits.
Weak plasmon modes in periodic structures for terahertz detection and amplification
Authors: Fateev D V , Polischuk O V , Morozov M Yu , Mashinsky K V , Moiseenko I M , Popov V V
Published: November 2021

Weak plasmon modes in periodic structures with a two-dimensional electron gas without an inversion center are studied theoretically. The asymmetry of the electric field and Fourier harmonics of weak plasmon modes can lead to the excitation of a travelling plasmon by an electromagnetic wave normally incident on the structure and to the appearance of nonlinear effects leading to the rectification of the incident radiation. The low radiation damping of weak plasmon modes can be used to increase the efficiency of terahertz plasmon amplifiers.
High-Q states in acoustic apple-shaped resonators
Authors: Igoshin Vladimir , Nikitina Anastasia , Tsimokha Mariia , Toftul Ivan , Petrov Mihail , Frizyuk Kristina
Published: November 2021

Apples play a significant role in our culture in various points of human history: starting from Adam and Eve, going on with Judgement of Paris, it also touches such great minds as Sir Isaac Newton and Alan Turing. Beyond that apples are still extremely relevant today due to Steve Jobs. In this work we study high quality (high-Q) resonant states of apple-shaped resonators. We have found that quasi bound states in continuum (quasi-BICs) are possible in the linear acoustic domain. We show that quasi-BICs are of Friedrich-Wintgen type, i.e. accompanied with avoided crossings while elongating or shrinking the apple-shaped resonator. Finally, we build a concise theory based on the group theory approach utilizing Wigner’s theorem. We illustrate that only the resonator symmetry plays major role, but not particular resonator’s shape.
Subwavelength probing of surface plasmons in magnetoplasmonic crystals
Authors: Frolov Aleksandr Yu , Verellen Niels , Moshchalkov Victor V , Fedyanin Andrey A
Published: November 2021

In this work, we report on near-field studying of propagating surface plasmons (SPs) in one-dimensional magnetoplasmonic crystals (MPCs) by aperture type scanning near-field optical microscopy (SNOM). Optical near-field around the aperture probe is used to drive SPs in the MPC locally. The SNOM signal represents the scattered intensity caused by the interaction of the SNOM probe near-field with the MPC. Scanning the MPC surface with polarization resolving of the scattered radiation shows decreasing of the intensity due to the SP excitation. The observed polarization dependence of the scattered SNOM signal is associated with the selective coupling of the near-field components of the SNOM probe with SPs. Finite-difference time-domain simulations reproduce the experimental SNOM signal. It is shown the excitation of SPs with symmetric (even parity) field distribution, which is forbidden for plane wave source at normal incidence.
Principal Component Analysis Applied to Gradient Fields in Band Gap Optimization Problems for Metamaterials
Authors: Gnecco Giorgio , Bacigalupo Andrea , Fantoni Francesca , Selvi Daniela
Published: November 2021

A promising technique for the spectral design of acoustic metamaterials is based on the formulation of suitable constrained nonlinear optimization problems. Unfortunately, the straightforward application of classical gradient-based iterative optimization algorithms to the numerical solution of such problems is typically highly demanding, due to the complexity of the underlying physical models. Nevertheless, supervised machine learning techniques can reduce such a computational effort, e.g., by replacing the original objective functions of such optimization problems with more-easily computable approximations. In this framework, the present article describes the application of a related unsupervised machine learning technique, namely, principal component analysis, to approximate the gradient of the objective function of a band gap optimization problem for an acoustic metamaterial, with the aim of making the successive application of a gradient-based iterative optimization algorithm faster. Numerical results show the effectiveness of the proposed method.
Dependence of the nonlinear optical response of CdSe nanoscrolls on coating with oleic or acetic acid
Authors: Golinskaya A D , Smirnov A M , Mantsevich V N , Kozlova M V , Kurtina D A , Vasiliev R B , Dneprovskii V S
Published: November 2021

The photoluminescence and nonlinear transmission of atomically thin population of colloidal CdSe rolled-up nanosheets were investigated at the one-photon stationary excitations of excitons by the third harmonic of Nd3+:YAP laser pulses. It was revealed that the nonlinear optical response of the nanoscrolls is strongly influenced by multiwalled rolled-up structure. The broadening of exciton band and the red shift of the photoluminescence were observed and explained by coupling effect within the folded scroll-layers.
Exceptional points in composite structures consisting of two dielectric diffraction gratings with Lorentzian line shape
Authors: Golovastikov Nikita , Bykov Dmitry , Doskolovich Leonid
Published: November 2021

Using scattering matrix formalism we derive analytical expressions for the eigenmodes of a composite structure consisting of two dielectric diffraction gratings with Lorentzian profile in reflection. Analyzing these expressions we prove formation of two distinct pairs of exceptional points, provide analytical approximations for their coordinates and by rigorous simulation demonstrate eigenmodes interchange as a result of encircling said exceptional points.
Single photon sources based on HPHT nanodiamonds
Authors: Kurochkin N S , Eliseev S P , Sychev V V , Gritsienko A V , Gorelik V S , Vitukhnovsky A G
Published: November 2021

Color centers in nanodiamonds are promising candidates for the creation of high-speed sources of single photons without blinking and degradation. Color centers in HPHT nanodiamonds have been investigated. The luminescence decay curves of color centers have been measured. Second order correlation functions were measured for nanodiamonds with sizes from 50 nm to 250 nm. Conclusions about the energy structure of color centers were made based on the correlation functions.
Mechanical deformation of atomically thin layers during stamp transfer
Authors: Ivanova Tatiana V , Permyakov Dmitry , Khestanova Ekaterina
Published: November 2021

The way transition metal dichalcogenide (TMD) strains during its transfer from one substrate to another is very interesting and holds a special place in the creation of heterostructures. In our work we observe the spectrum of photoluminescence in TMD during the transfer. For this we use a specially designed transfer system with inverted geometry. During transfer we observe a modification of exciton photoluminescence linewidth and resonance shift in atomically thin layers of TMD. We believe that our results lay grounds for the future work on the assessment of the atomically thin layer inhomogeneity introduced by the typical mechanical transfer.
Linear optical properties of HKUST-1 metal-organic framework: Effect of the crystal size and synthetic approach
Authors: Kenzhebayeva Yuliya A. , Bachinin Semyon , Gilemkhanova Venera , Milichko Valentin A.
Published: November 2021

We evaluated the change in the transmission and reflection spectra of single rhombic dodecahedron nanocrystals of the metal organic frameworks HKUST-1 with and without effect of near infrared laser radiation. The analysis of commercial and synthesized in the laboratory compounds was made through the optical transmittance and reflectance spectroscopy. Moreover, electronic microscopy and light scattering on the microcrystals was also utilized for revealing the size dependent colour. Such studies may find new application for MOF nanocrystals, as well as gain additional information about their usage for biological purposes or in computer sensing.
Light-induced electron pairing in two-dimensional systems
Authors: Kibis O. V. , Boev M. V. , Kovalev V. M.
Published: November 2021

The mechanism of electron pairing induced by a circularly polarized off-resonant electromagnetic field is suggested and examined theoretically for various two-dimensional (2D) nanostructures. Particularly, it is demonstrated that such a pairing can exist in 2D systems containing charge carriers with different effective masses. As a result of the pairing, the optically induced hybrid Bose-Fermy system appears. The elementary excitation in the system are analyzed and the possible Bose-Einstein condensation of the paired electrons and the related light-induced superconductivity are discussed.
Optomechanical interaction between single-walled carbon nanotubes of various structures
Authors: Kislov D , Kushchenko O , Shalin A S
Published: November 2021

We consider optomechanical interaction in an asymmetric structure of a carbon nanotubes dimer of different orientations and/or different atomic structures in the field of a plane wave or a focused Gaussian beam. Here we show that optical coupling in such the system can lead to nonreciprocal interactions between the constituents. We demonstrate that a non-conservative force is applied to the center of mass of an optically coupled nanotube dimer, resulting in an unexpected lateral action. The sign and magnitude of this force depend on abrupt phase transitions in the properties of the asymmetric dimer.
Continuous-Flow Synthesis of Perovskite Particles for Optical Application
Authors: Koryakina Irina , Bikmetova S , Arabuli K , Evstrapov A , Pushkarev A , Makarov S , Zyuzin M V
Published: November 2021

Conventional chemical synthesis methods for nanomaterials fabrication do not always provide precise reproducible synthesis with controllable physicochemical parameters. A better control over the resultant properties of nanomaterials can be achieved by scaling down the synthesis approach to the microlevel. This can be realized by means of microfluidics. In this work, a microfluidic approach is applied for the controllable synthesis of perovskite particles with defined cubic morphology. The structural characterization of perovskite particles is performed using scanning electron microscopy and X-ray diffraction. All the synthesized particles demonstrate photoluminescence.
2D Perovskite Micro-optics Enabled by Direct Femtosecond-Laser Projection Lithography
Authors: Cherepakhin A. , Zhizhchenko A. , Porfirev A. , Pushkarev A. , Makarov S. , Kuchmizhak A.
Published: November 2021

Using direct femtosecond-laser projection lithography in chemically synthesized CsPbBr3 perovskite microcrystals we demonstrate high-throughput fabrication of advanced binary microscale optical elements for nanofocusing as well as generation of high-order optical vortex beams. The obtained results highlight the CsPbBr3 microcrystals as a promising material for realization of various complicated 2D micro-optical elements and holograms that can be directly imprinted using non-destructive and practically relevant laser technologies.
Switchable Purcell enhancement of photoluminescence by GST film
Authors: Kushchenko O M , Sinelnik A D , Shishkin I I , Gets D S , Makarov S V , Rybin M V
Published: November 2021

In the present paper perovskite radiation enhancement on crystalline GST film compared to amorphous one has been studied. The photonic local density of states has been calculated by angular spectrum representation of the dyadic Green’s function. The Purcell factor has been calculated for perovskite luminescent on both amorphous and crystalline GST film. Almost 80% enhancement has been observed at wavelength 950 nm for system with perovskite thickness 25 nm, GST thickness 110 nm.
Transformation of guided modes into bound states in the continuum
Authors: Kutuzova Aleksandra A. , Rybin Mikhail V.
Published: November 2021

We study a silicon-based structure composed of parallel rods arranged in a periodic array. The structure supports guided modes which due to the deformation of structure in general become leaky modes. At the same time the modes split at the Brillouin zone surface by a pair with certain symmetry. Here we report on guided modes transformation into symmetry-protected BIC under deforming the structure, because of inherent field distribution governed by the Bragg-related mode hybridization.
Bound states in the continuum-induced enhancement of evanescent field confinement
Authors: Lepeshov S I , Bogdanov A A
Published: November 2021

Here, the enhancement of electromagnetic field confinement in an all-dielectric metasurface is demonstrated. The enhanced confinement is achieved when the polarization singularity, corresponding to accidental bound states in the continuum, moves to the domain of evanescent fields (under the light line). Such a hybridization of the bound states and evanescent waves results in the 70-fold increase of the electric field enhancement on the top of the metasurface and boosting of the electric field localization.
Atmospheric Propagation Of SubTHz Waves And Space, 6G & 7G Communications
Authors: Ilya Lesnov , Vyacheslav Vdovin
Published: November 2021

The work is devoted to the actual problem of data rate of wireless telecommunication channels. Presented analysis of the telecommunication channel subterahertz (subTHz) frequency range - as the most promising band for the implementation of wireless telecommunications for space links and terrestrial cellular communications of high capacity. A channel considered as a combination of high effective transponder / transmitter duplex together with an open high dissipative atmospheric line. The means to achieve a high signal / noise ratio is usage of low-noise cryogenic receivers. The theoretical analysis of data rates for various atmospheric conditions and technical implementations of communication channels demonstrated reasonable limits of cooling of receivers, providing a weighty increase channel capacity, while deeper cooling is impractical due to weather restrictions in certain ranges and conditions of signal propagation, including altitude and seasonal features.
Anion Exchange Reaction in Halide Perovskite Single Crystals Structured by Laser Pulses
Authors: Zhizhchenko Yu A , Masharin M , Pushkarev A , Kuchmizhak A A , Makarov S V , Kulinich S A
Published: November 2021

In this work, we carry out chemical processing of halide perovskite (CsPbBr3) microplates, where microlenses can be formed on surface by laser ablation by femtosecond laser ablation. Namely, we perform anion exchange reaction and observe spectral tuning of the microplates optical properties. We believe this effect will open new opportunities for tunable and reconfigurable micro-optical devices.
Experimental study of nonlinear absorption in hyperbolic metamaterials based on ordered arrays of nanorods
Authors: Malysheva I.V. , Kolmychek LA. , Leontiev A. P. , Napolskii K.S. , Murzina T. V.
Published: November 2021

Nanophotonics is a rapidly developing branch of physics that studies light interaction with nanoscaled objects such as metamaterials. Hyperbolic metamaterials (HMMs) based on ordered arrays of metal nanorods embedded in a dielectric matrix are of great interest due to their nontrivial optical properties and abilities to control over the parameters of light. In this article, we present the results of nonlinear absorbtion measurements in HMMs based on ordered arrays of silver nanorods. The main finding consists in the spectral vicinity of Epsilon-Near-Zero and Epsilon-Near-Pole features.
Theoretical study of perovskite nanowires optical response to hydrogen halides vapor exposure
Authors: Markina D. I. , Pushkarev A.P. , Makarov S.V.
Published: November 2021

Highly sensitive detection of harmful to the human health and environment hydrogen halide vapors is one of the key problems for the chemical industry. The available electrochemical and optical sensors most often show no selectivity to different hydrogen halides and can be produced via costly high-tech fabrication. In contrast to them, CsPbBr3 perovskite nanowires (NWs) exhibiting laser generation are capable of selective and precise detecting for HCl and HI. Exposure of a single NW to these analytes results in an anion exchange that modifies the chemical composition of the NW and therefore invokes a small spectral shift of the laser peak. Herein we propose a theoretical model describing such an optical response. Taking into account that the anion exchange occurs at the surface of the NW and initiates the formation of a core-shell structure, we perform numerical estimation of the eigenmode spectral position for different thicknesses of the chlorine-and iodine-rich shell. Calculations reveal that even a 10 nm shell causes a noticeable spectral shift of 0.81 and 0.63 nm for eigenmode in CsPbBr3-CsPbCl3 and CsPbBr3-CsPbl3 core-shell NWs, respectively.
Charge carriers drift induced THz amplification in dual-layer graphene structure
Authors: Moiseenko I.M. , Popov V.V. , Fateev D.V.
Published: November 2021

The terahertz plasmon amplification in structure based on graphene with spatial dispersion of its hydrodynamic conductivity is investigated theoretically. The spatial dispersion of graphene conductivity is related to accounting of charge carriers pressure forces and direct current in graphene. It was shown that the real part of graphene conductivity becomes negative at THz frequency range due to direct electric current in graphene.
Effect of longitudinal epsilon-near-zero regime in dynamics of ultrashort laser pulses in hyperbolic metamaterials
Authors: Novikov Vladimir
Published: November 2021

Optical properties of hyperbolic metamaterials (HMMs) are in stark contrast to properties of ordinary media that fuels interest to various applications of HMMs in photonics. Special attention is attributed to the epsilon-near zero regime (ENZ) of HMMs that is the spectral point in which real part of the permittivity of the HMM becomes zero. This is accompanied by the effects of field enhancement having far-reaching applications. Here we focus on the experimental and theoretical investigation of the propagation of an ultrashort laser pulse through the silver nanorod-based HMM slab in the spectral range over the ENZ. We revealed pronounced resonant change of the pulse delay in HMMs and the transition between the superluminal and slow pulse propagation at the ENZ spectral point. Observed dynamical phenomena are confirmed theoretically and attributed to unusual case when the spectral half of an ultrashort pulse has elliptical dispersion and another has the hyperbolic one. Special attention is payed to the propagation of chirped laser pulses in the HMMs.
Ultrafast laser heating of non-plasmonic nanocylinders
Authors: Pashina Olesia , Ryabov Daniil , Zograf George , Makarov Sergey , Petrov Mihail
Published: November 2021

We develop a model describing non-equilibrium processes under the excitation of resonant semiconductor nanostructures with ultrashort laser pulses with a duration of about 100 fs. We focus on the heating effects related to pulsed excitation with account on free carriers generation, thermalization, and relaxation. The heat exchange between the electron and phonon system is treated within the two-temperature model. We applied the developed model to describing pulsed heating of silicon nanocylinder on top of a dielectric substrate. We come up with estimations of the thermal damage threshold of the considered structures which provides the limits for the experimental conditions and ensures thermal stability of the samples.
Nontrivial optical response of silicon triangular prisms
Authors: Poleva M , Baryshnikova K V , Frizyuk K , Evlyukhin A B
Published: November 2021

The electromagnetic response of silicon triangle nanoprisms in the near-infrared region is investigated. It is revealed that the bianisotropic dipole approximation is insufficient for this geometry since the direct application of the Onsager-Casimir symmetry rule to the dipole response leads to a contradictory conclusion. We show that to resolve this contradiction, it is necessary to take into account the nonlocal contributions of higher orders to the excited electric and magnetic dipole moments of the prisms. However, the inclusion in the consideration of nonlocal corrections to the dipole moments leads to the need to take into account the excitation of multipoles of a higher order than dipoles.
Second-harmonic generation from green printed selenium structures
Authors: Yu. Ponkratova E. , Sun Y. , Zhang Z. , Su M. , Mikhailova Y. V. , Zuev D.A. , Song Y. , Kumar S. , Ganguli A.K. , Belov P. A.
Published: November 2021

Plenary large-scale efficient second-harmonic generation sources remains a challenge in micro-/nanoscale research. In this work, we demonstrate the strong second-harmonic generation in arrays of selenium particles fabricated by green printing method at the pumping wavelength of 1047 nm. Second-harmonic generation mapping shows the strong signal over the whole area of selenium particle. We propose, that such structures can be a perspective platform for efficient frequency conversion systems and nonlinear sensing applications.
Enhancement of the photocatalytic activity of nanoparticles due to the localization of electromagnetic fields
Authors: Ponomareva S R , Gurvitz E A , Ladutenko K S
Published: November 2021

In this work, we consider the designs of nanoparticles based on titanium dioxide. We focus on localizing energy in the near-surface layer of particles in order to increase the generation of electron-hole pairs in this region. This should result in an enhancement in their photocatalytic activity.
Comparison of different wireless coils for 1.5 T bilateral breast MRI
Authors: Puchnin Viktor , Nikulin Anton , Hurshkainen Anna , Solomakha Georgiy , Andreychenko Anna , Shchelokova Alena
Published: November 2021

In this work, we compare three types of transceive wireless coils: Helmholtz-type coil, metamaterial-inspired coil and their combination. Each transceive coil is electromagnetically coupled to a body coil “birdcage” type of a 1.5 T MR scanner and improves bilateral breast imaging performance. While Helmholtz-type coil and metamaterial-inspired coil based on coupled split loop resonators are linearly polarized, their combination allows to couple with both linear components of the radiofrequency magnetic field, providing a more significant effect of a local boosting of the body coil’s transmit efficiency and radiofrequency safety in comparison with birdcage coil only.
Propagation and scattering effects in temporal metastructures
Authors: Ramaccia D. , Alù A. , Toscano A. , Bilotti F.
Published: November 2021

Electromagnetic scattering typically occurs when a change in the material properties is perceived by the propagating wave, that inevitably splits into a reflected and refracted wave to maintain the continuity of the field components at the interface between the two media. However, such a scattering phenomenon occurs also when the entire media suddenly switches its properties to other values at a certain instant of time, realizing the so-called temporal interface. After a temporal interface, a couple of waves, one reflected and one transmitted, starts to propagate in the new media with the same wavelength but at a different frequency. Exploiting the analogies and differences between spatial and temporal interfaces, in this contribution we present the temporal counterparts of conventional electromagnetic devices based on dielectric slabs and a cascade of them, i.e., the multilayered structures. We discuss about the analysis and design strategies for synthetizing the desired scattering response in both transmission and reflection and present the possible families of devices based on multi-switched temporal metamaterials that can be conceived.
Topological edge states of anyon pairs emulated in electric circuits
Authors: Rozenblit A D , Olekhno N A , Dmitriev A A , Seregin P S , Gorlach M A
Published: November 2021

Recent advances in two-particle topological quantum states demonstrate resilience to geometrical imperfections and hold perspectives for robust quantum computations. In this context, particles with fractional quantum statistics, the so-called anyons, attract especial attention. In particular, topological edge states of anyon pairs in one-dimensional chains of coupled cavities were recently predicted to demonstrate localization at one or another edge of the array depending on details of the quantum statistics. In this paper, propose an equivalent electric circuit serving as a classical emulator of such topological states. Detailed numerical studies of resonances in the circuit fully support theoretical predictions, pointing towards future experimental realizations of anyonic states analogs in electrical circuits.
A Facile Route of Manufacturing of Silicon-Based Nanostructures with Tuned Plasmonic Properties
Authors: Flimelova Miroslava , Ryabchikov Yury V
Published: November 2021

An environment-friendly method of pulsed laser ablation in liquids is successfully employed for structural modification of silicon nanoparticles leading to a considerable narrowing of their size distribution accompanied with a reduction of the mean size. Contamination-free conditions of synthesis ensure the chemical purity of formed nanostructures that may reduce toxicity issues. Such a laser-induced modification leads to the appearance of plasmonic properties in semiconductor-based nanomaterials. Their spectral position can easily be varied in the whole visible range. Combined in one nanoparticle properties of semiconductors and noble metals can strongly promote applications of composite laser-synthesized nanoparticles for biosensing (using their plasmonic-based surface-enhanced ability) and bioimaging (using their both optical and magnetic abilities) purposes.
Anomalous anti-Stokes Scattering in Amorphous Carbon Thin Films
Authors: Saparina S V , Gazizov A R , Kharintsev S S
Published: November 2021

This work is devoted to a study of temperature-dependent Raman scattering of amorphous carbon (a-C) thin films. An anomalous rise of the anti-Stokes intensity in respect to the Stokes intensity was observed. This result comes from the resonant enhancement of anti-Stokes scattering of defects of graphite-like crystals. The observed discrepancy is quantified through a coefficient, a, defined as a ratio of the anti-Stokes and Stokes scattering cross sections. Understanding the mechanism for anomalous enhancement of anti-Stokes scattering provides a way for correct probing the temperature of the a-C thin films exposed to cw laser illumination.
Application of the SENSE Algorithm to Multimodal Switchable Metasurface Imaging
Authors: Seregin P , Kretov E , Smolka K , Zubkov M
Published: November 2021

This work aims to provide a way of performing parallel imaging with a single-channel variable-frequency resonant device. Different spatial sensitivity profiles required for SENSE reconstruction are achieved by switching between the device eigenmodes. A device capable of such switching is manufactured and several k-spaces are acquired using the device different eigenmodes. The k-spaces are then subject to downsampling to obtain the sensitivity profiles of each eigenmode and then - to perform SENSE-based reconstruction of the unaliased images with different acceleration factors.