bluuebunny/crossref_metadata_2025 huggingface dataset:
Aquifer system and groundwater potency in coastal area of Kretek, Bantul Regency, Indonesia
Authors: Saleh Isa La Ode , Setyawan Purnama Ignasius Loyola
Published: November 2021

The existence of groundwater in coastal areas really needs attention because of its vulnerability to sea water intrusion. Utilization and good management are needed to maintain its sustainability. The purpose of this research is to determine the aquifer system in the study area and to calculate the groundwater potency. The aquifer system is determined by processing geoelectric sounding data using Rockworks 16 software. Groundwater potency is calculated using a static approach. The safe yield of groundwater is calculated by multiplying of groundwater fluctuation, village area and the specific yield. Water requirement is calculated base on domestic, livestock and tourism water requirement. The results showed that the Kretek District had two aquifer units, namely the fluvio marin plains and sand dunes. In the fluvio marin plains, most of the constituent material is sand with clay as inserts, while in the aquifer unit the sand dune has constituent material in the form of unconsolidated sand originating from the Merapi Volcano. The groundwater potency of the study area is 234,448,0000 m3/year and the safe yield is 11,772,400 m3/year. With the water requirement for domestic, livestock and tourism are 555,044 m3/year, the groundwater potency in the study area is still sufficient. However, it is recommended that the well drilling does not exceed a depth of 40 meters, because at several locations there has been detected an interface. In addition, in several locations there were also detected connate water originating from ancient marines during the deposition process of the fluvio marin plains in the past.
Identification of Karst Underground River Catchment Areas with Artificial Tracer Tests and Water Balance in Banteng Cave Springs (Karst Gombong Selatan, Central Java)
Authors: Al-Ghozali Muhammad Qodri , Adji Tjahyo Nugroho , Haryono Eko , Cahyadi Ahmad , Agniy Romza Fauzan , Laksono Gangsar Edi , Priambada Alpine Prima , Rahmawati Aulia Ika , Mahrizkhal Danung Shodikh , Setiawan Andy , Fauzi Danang Riza , Astuti Elisabeth Supi , Putra Rahmat Dwi , Biladi Muslih
Published: November 2021

The karst hills of Gombong Selatan have abundant potential water resources, especially in locations that have underground springs and rivers. The connectivity between the subsurface passageways that is difficult to know can threaten the potential of water resources, one of which is due to pollution caused by uncontrolled human activities. Therefore, identification of catchment systems and boundaries of water catchment areas in karst aquifers is needed that can contribute to sustainable water resources management policies. This catchment identification needs to be conducted because previous studies have never explored the eastern side of this karst area. This study aims to (1) define the underground river flow connectivity (upstream-downstream) of Banteng Cave; and (2) limiting the water catchment area of Banteng Cave. The method used to determine the subsurface connectivity system was carried out through an artificial tracer test, while the catchment area was delineated using a water balance approach. The results showed that the underground river of Banteng Cave has connectivity with Lake Blembeng, as evidenced by a change in watercolour after the tracer test and breakthrough curve (BTC) analysis of the tracing test results. BTC analysis shows that the Banteng Cave passageway has one main passage and does not have a tunnel branch. The estimated area of the Banteng Cave catchment used a water balance approach, which is 141.73 hectares. The Banteng Cave karst catchment conditions are dominated by the formation of valleys and karst cones accompanied by the appearance of valleys and karst hills that are quite evenly distributed, indicating that the Banteng Cave karst catchment is included in the advanced karst development phase. Furthermore, this research contributes significantly to increase knowledge regarding the characteristics of void karst development in aquifers which in the future are very important for determining water resources management policies.
The Implementation of Kruskal’s Algorithm for Minimum Spanning Tree in a Graph
Authors: Paryati  , Salahddine Krit
Published: November 2021

Kruskal’s Algorithm is an algorithm used to find the minimum spanning tree in graphical connectivity that provides the option to continue processing the least-weighted margins. In the Kruskal algorithm, ordering the weight of the ribs makes it easy to find the shortest path. This algorithm is independent in nature which will facilitate and improve path creation. Based on the results of the application system trials that have been carried out in testing and comparisons between the Kruskal algorithm and the Dijkstra algorithm, the following conclusions can be drawn: that a strength that is the existence of weight sorting will facilitate the search for the shortest path. And considering the characteristics of Kruskal’s independent algorithm, it will facilitate and improve the formation of the path. The weakness of the Kruskal algorithm is that if the number of nodes is very large, it will be slower than Dijkstra’s algorithm because it has to sort thousands of vertices first, then form a path.
X-rays Image reconstruction using Proximal Algorithm and adapted TV Regularization
Authors: Allag Aicha , Drai Redouane , Boutkedjirt Tarek , Benammar Abdessalam , Djerir Wahiba
Published: November 2021

Computed tomography (CT) aims to reconstruct an internal distribution of an object based on projection measurements. In the case of a limited number of projections, the reconstruction problem becomes significantly ill-posed. Practically, reconstruction algorithms play a crucial role in overcoming this problem. In the case of missing or incomplete data, and in order to improve the quality of the reconstruction image, the choice of a sparse regularisation by addingl1norm is needed. The reconstruction problem is then based on using proximal operators. We are interested in the Douglas-Rachford method and employ total variation (TV) regularization. An efficient technique based on these concepts is proposed in this study. The primary goal is to achieve high-quality reconstructed images in terms of PSNR parameter and relative error. The numerical simulation results demonstrate that the suggested technique minimizes noise and artifacts while preserving structural information. The results are encouraging and indicate the effectiveness of the proposed strategy.
Preliminary Results of Endoscopic Radiofrequency Treatment of the Sacroiliac Joint Syndrome
Authors: Woiciechowsky Christian , Richter Leonie Mercedes
Published: November 2021

Background and Study The sacroiliac joint (SIJ) may be the primary source of pain in 15 to 25% of patients with axial low back pain. Furthermore, 75% of patients who have had fusion surgery develop SIJ pain within 10 years. Treatment options include SIJ blocks, radiofrequency (RF) denervation, and fusion. The RF techniques range from ablation of the nerves supplying the joint, creating lesions to the joint itself, or a combination of both techniques. However, different clinical studies could only identify a limited or, in some cases, no effect in decreasing of pain intensity and duration of the effect.

Methods In this retrospective study, we selected 23 patients with SIJ pain, with a duration of more than 12 months and a 50% pain reduction on the Numeric Rating Scale (NRS) after diagnostic block. All patients received endoscopic ablation of the medial branch L5/S1 and the lateral branches, exiting the sacral foramina on S1/S2 and S2/S3 on both sides while using only one incision on each side. Telephone interviews were conducted with all patients. The outcome was determined with Odom's criteria, percent reduction NRS, subjective assessment of the patient, and duration of the effect.

Results According to Odom's criteria, 79% of the patients showed acceptable to excellent results and confirmed that denervation helped them to manage their daily lives better. The average pain reduction in the responder group was 57% with an average duration of 13.4 months.

Conclusion In this retrospective study, we could demonstrate the practicability and effectiveness of endoscopic SIJ denervation in the treatment of SIJ pain using only one incision for three levels on each side. Further studies should investigate if this procedure is more effective than percutaneous RF.
The economic dimension of migration: Kosovo from 2015 to 2020
Authors: Hajdari Labinot , Krasniqi Judita
Published: November 2021

This article investigates the link between economic development and emigration from Kosovo between 2015 and 2020. The wider contexts to this study include the empirical and theoretical debates on migration as both an individual choice and a social decision. The recent history of emigration from Kosovo is analysed to understand how the past has influenced present migration patterns. This work aims to unpick the threads connecting economic development, the labour market, educational disparities, unemployment, and EU integration. Demographics, economics, and the political relationship between Kosovo and the EU have all affected emigration trends in Kosovo. In particular, this article examines the brain drain phenomenon and economic stability as two variables that permanently influence one another.
Machine learning methods for “wicked” problems: exploring the complex drivers of modern slavery
Authors: Lavelle-Hill Rosa , Smith Gavin , Mazumder Anjali , Landman Todd , Goulding James
Published: November 2021

Forty million people are estimated to be in some form of modern slavery across the globe. Understanding the factors that make any particular individual or geographical region vulnerable to such abuse is essential for the development of effective interventions and policy. Efforts to isolate and assess the importance of individual drivers statistically are impeded by two key challenges: data scarcity and high dimensionality, typical of many “wicked problems”. The hidden nature of modern slavery restricts available data points; and the large number of candidate variables that are potentially predictive of slavery inflate the feature space exponentially. The result is a “small n, large p” setting, where overfitting and significant inter-correlation of explanatory variables can render more traditional statistical approaches problematic. Recent advances in non-parametric computational methods, however, offer scope to overcome such challenges and better capture the complex nature of modern slavery. We present an approach that combines non-linear machine-learning models and strict cross-validation methods with novel variable importance techniques, emphasising the importance of stability of model explanations via a Rashomon-set analysis. This approach is used to model the prevalence of slavery in 48 countries, with results bringing to light the importance of new predictive factors—such as a country’s capacity to protect the physical security of women, which has been previously under-emphasised in quantitative models. Further analyses uncover that women are particularly vulnerable to exploitation in areas where there is poor access to resources. Our model was then leveraged to produce new out-of-sample estimates of slavery prevalence for countries where no survey data currently exists.
Factors of feasibility: an interview study of physicians’ experiences of expanded access to investigational drugs in three countries
Authors: Vermeulen Stefan F. , Hordijk Marjolijn , Aarts Nikkie , Bunnik Eline M.
Published: November 2021

Seriously ill patients who have exhausted all approved treatment regimens and who cannot be enrolled in clinical trials may resort to expanded access programmes in order to gain access to unapproved, investigational drugs. It seems that in some countries, expanded access to investigational drugs is offered in clinical practice on a more routine basis than in other countries. This study is the first to investigate the experiences of physicians with expanded access to investigational drugs in different healthcare systems, with a focus on factors that facilitate or hinder expanded access. Semi-structured interviews (n = 36) were carried out with medical specialists in the Netherlands (n = 14), Turkey (n = 9) and the United States of America (n = 13), and analysed thematically. This study identifies five sets of factors pointed out by physicians that determine the degree to which expanded access to investigational drugs is deemed feasible in clinical practice: the suitability of investigational treatments, the application process, hospital policies, support by pharmaceutical companies, and funding and reimbursement arrangements. Based on the interviews conducted, we conclude that, while legally allowed and technically possible, expanded access is not always feasible for—and not always considered an option by—treating physicians. This is mainly due to lack of familiarity with expanded access, the extensive time and effort required for the application process, willingness or ability of pharmaceutical companies to supply the drugs, and funding issues.
A review on low-dimensional novel optoelectronic devices based on carbon nanotubes
Authors: Li Yu-Tao , Sun Kuan , Luo Di , Wang Yi-Ming , Han Lei , Liu Hang , Guo Xiao-Liang , Yu Du-Li , Ren Tian-Ling
Published: November 2021

With the development of integrated circuits according to Moore’s law, traditional silicon-based devices have gradually reached their performance limitation. Nanoelectronics based on carbon nanomaterials provides a broad prospect for the continuation of Moore’s law. In particular, in the field of optoelectronic devices, it is necessary to further develop new types of nano-optoelectronic devices. Carbon nanotubes (CNTs) are one of the representative materials of nanoelectronics with excellent electrical and optical properties, e.g., high mobility, suitable band structure, and good infrared absorption. The application of CNTs in optoelectronic devices is a very attractive research topic, which has been developed rapidly in recent years. Until now, various prototypes of CNT-based optoelectronic devices have been developed. In this Review, we briefly introduce the structure and photoelectric properties of CNTs. Then, according to different photo-electron coupling mechanisms, four types of CNTs based on optoelectronic devices are introduced in detail, namely, solar cells, photodetectors, light-emitting diodes, and lasers. Intrinsic and composite CNT-based optoelectronic devices are presented in order to describe the development of CNT-based optoelectronic devices. Finally, different material preparation, separation, and mixing methods of CNTs are discussed, which are the methods for basic material preparation for the fabrication of high performance CNT-based optoelectronic devices. An in-depth study of the development trend of CNT-based optoelectronic devices will contribute to the future development of novel high-performance nanoelectronic devices.
Understanding and design of efficient carrier-selective contacts for solar cells
Authors: Wang Guangyi , Zhang Chenxu , Sun Heng , Huang Zengguang , Zhong Sihua
Published: November 2021

Numerous efforts have been devoted to either understanding or fabricating efficient carrier-selective contacts, since they play a significantly crucial role in high-performance solar cells. In this work, we demonstrate that the asymmetry between electron conductivity and hole conductivity is important but far not enough for efficient carrier-selective contacts. Taking electron-selective contacts as examples, cell performances are greatly affected by the electron conductivity, the hole conductivity, and the work function of electron-selective materials, together with conduction and valance band offset between absorbers and electron-selective layers. When designing efficient electron-selective contacts, all these factors should be considered to mitigate carrier recombination and downward bending of the electron quasi-Fermi level within and around the contacts and to ensure low interfacial resistance for electrons. Although the absorber is crystalline silicon in the study, we believe that our understanding and design guidelines are also applicable to solar cells based on other absorbers.
Strain tunable intrinsic ferromagnetic in 2D square CrBr2
Authors: Li Fei , Ren Yulu , Wan Wenhui , Liu Yong , Ge Yanfeng
Published: November 2021

Two-dimensional intrinsic magnetic materials with high Curie temperature (Tc) coexisting with 100% spin polarization are highly desirable for realizing promising spintronic devices. In the present work, the intrinsic magnetism of monolayer square CrBr2 is predicted by using first-principles calculations. The monolayer CrBr2 is an intrinsic ferromagnetic half-metal with the half-metallic gap of 1.58 eV. Monte Carlo simulations based on the Heisenberg model estimate Tc as 212 K. Furthermore, the large compressive strain makes CrBr2 undergo ferromagnetic–antiferromagnetic phase transition when the biaxial tensile strain larger than 9.3% leads to the emergence of semiconducting electronic structures. Our results show that the intrinsic half-metal with a high Tc and controllable magnetic properties endow monolayer square CrBr2 as a potential material for spintronic applications.
Focusing grating couplers for radio-frequency surface ion traps
Authors: Abbasov Timur , Kazakov Ivan , Sherstov Ivan , Kontorov Sergey , Shipulin Arkadi , Kueppers Franko , Lakhmanskiy Kirill
Published: November 2021

We present a photonic integrated circuit design with multiple focusing grating couplers that can be used in a surface ion trap. This system allows transferring laser radiation from different laser sources to the ion trapped 240 μm above the surface for further manipulations.
Chiral light in single-handed Fabry-Perot resonators
Authors: Taradin Alexey , Baranov Denis G.
Published: November 2021

Chirality is a universal phenomenon that is encountered on many different length scales in nature. Interaction of chiral matter with chiral light results in the effect of circular dichroism, which underlies many techniques of discriminating molecular enantiomers. Enhancing dichroic effects is typically achieved by interfacing chiral matter with various optical resonators. In this context it is important to understand how the eigenmodes of optical cavities relate to the field states with well-defined handedness. Here, we present the model of a single-handedness chiral optical cavity supporting only an eigenmode of a given handedness without the presence of modes of other helicity. Resonant excitation of the cavity with light of appropriate handedness enables formation of a helical standing wave with a uniform chirality density, while the opposite handedness does not cause any resonant effects. Our findings expand the set of tools for investigations of chiral matter and open the door towards studies of chiral electromagnetic vacuum states.
Multi wall carbon nanotubes as a top electrode for perovskite light-emitting electrochemical cells
Authors: Bodyago Elena , Gets Dmitry , Baeva Maria , Mukhin Ivan , Makarov Sergei , Zakhidov Anvar
Published: November 2021

Carbon nanotubes are promising materials for use as flexible and transparent electrodes for a wide variety of optoelectronic devices like solar cells and light-emitting diodes. Moreover, the chemical inertness of carbon nanotubes matches with the operation of light-emitting electrochemical cells where ion migration is a main working principle especially based on halide perovskite, in which ions corrode metal electrodes. Here we demonstrate how the removal of synthesis residuals via synthesis enables the use of multiwall carbon nanotubes as a transparent electrode.
Optical properties of new hybrid nanoantenna in submicron cavity
Authors: Gritsienko A V , Kurochkin N S , Lega P V , Orlov A P , Ilin A S , Eliseev S P , Vitukhnovsky A G
Published: November 2021

An essential area of nanophotonics is the creation of efficient quantum emitters operating at high frequencies. In this regard, plasmon nanoantennas based on nanoparticles on metal (nanopatch antennas) are incredibly relevant. We have created and investigated a new hybrid nanoantenna with a cube on metal and quantum emitters. We demonstrate an increase up to 60 times for the rate of spontaneous emission and the gap-plasmon mode changing for nanopatch antenna in the metallic well. The results show the possibility of creating plasmon antennas in a controlled way by creating an array of regularly arranged nanoscale cavities-resonators.
Broadband metasurfaces loaded with non-Foster elements
Authors: Kalmykov Nikita , Buiantuev Bair , Kholodnyak Dmitry
Published: November 2021

Metasurfaces have been widely used to design low-profile antennas, thin absorbers, lenses etc. The operational frequency band of a metasurface is rather narrow due to its resonant nature. Loading metasurface unit cells with non-Foster elements allows for remarkable bandwidth extension. In this paper, design of a broadband metasurface to operate as an artificial magnetic conductor is considered. The main issues which influence the bandwidth extension such as implementation of the non-Foster load, minimization of conversion error of a negative impedance converter, and circuit stabilization are addressed.
Floquet engineering of carbon nanotubes
Authors: Kibis O. V. , Boev M. V. , Kovalev V. M.
Published: November 2021

The Floquet theory for electrons in carbon nanotubes (CNTs) irradiated by a circularly polarized electromagnetic wave propagating along the CNT axis is developed. It is demonstrated, particularly, that the irradiation opens the gap between the conduction and valence bands of CNTs of metal type and lifts the degeneracy of electron states with mutually opposite angular momenta along the CNT axis. As a consequence, the optically-induced metal-insulator transition and the optical Zeeman effect appear in the CNTs. It follows from the theory that these light-induced phenomena can be observed in the modern experiments.
Second-harmonic generation enhancement in high-contrast micropillar AlGaAs resonator in bound states in the continuum regime
Authors: Kolodny Stanislav , Kozin Valerii , Iorsh Ivan
Published: November 2021

It has been shown that the use of micropillar resonators, which comprise a cylindrical semiconductor cavity sandwiched between the Bragg mirrors can substantially increase the quality factor preserving the mode volume, and thus substantially enhance the local fields. Here, we show that these structures indeed can facilitate the significant enhancement of the SHG efficiency. We provide a specific design of the AlGaAs pillar microcavity and use the numerical modelling to directly show the resonant enhancement of the SHG efficiency. We believe that the presented results would be of high interest to the nanophotonic community, especially in nonlinear optics field.
Silicon nanowires as multi—environment sensor elements for carbon monoxide and ammonia detection
Authors: Kondratev V. M. , Morozov I.A. , Vyacheslavova E.A. , Gudovskikh A. S. , Nalimova S. S. , Moshnikov V.A. , Bolshakov A. D.
Published: November 2021

Carbon monoxide and ammonia are inorganic agents found both in nature and in the human body, which is of great interest for modern sensing. First, in concentrations of the order of 1 ppm agents are produced by human and can be markers of changes in human health. Second, at concentrations of the order of 100 ppm, carbon monoxide and ammonia are toxic and hazardous. This work is aimed at fabrication and study of precise, technological and relatively cheap sensors compatible with a gas and liquid medium for CO and NH3 detection, respectively.
Probing guided monolayer semiconductor polaritons below the light line
Authors: Kondratyev V. , Permyakov D. , Kravtsov V. , Krizhanovskii D. N. , Samusev A. K.
Published: November 2021

In this work, we demonstrate an approach to study exciton-polaritons supported by transition metal dichalcogenide monolayers coupled to an unstructured planar waveguide below the light line. In order to excite and probe such waves propagating along the interface with the evanescent fields exponentially decaying away from the guiding layer, we employ a hemispherical ZnSe solid immersion lens (SIL) precisely positioned in the vicinity of the sample. We visualize the dispersion of guided polaritons using back focal (Fourier) plane imaging spectroscopy with the high-NA objective lens focus brought to the center of SIL. This results in the effective numerical aperture of the system exceeding an exceptional value of 2.2 in the visible range. In the experiment, we study guided polaritons supported by a WS2 monolayer transferred on top of a Ta2O5 plane-parallel optical waveguide. We confirm room-temperature strong light-matter coupling regime enhanced by ultra-low intrinsic ohmic and radiative losses of the waveguide. Note that in the experiment, total radiative losses can be broadly tuned by controlling SIL-to-sample distance. This gives a valuable degree of freedom for the study of polariton properties. Our approach lays the ground for future studies of light-matter interaction employing guided modes and surface waves.
Doubly excited states in a chiral waveguide-QED system: description and properties
Authors: Kornovan D. , Vlasiuk E. , Poddubny A. , Petrov M.
Published: November 2021

In modern quantum optics chiral waveguide quantum-electrodynamical (wQED) systems are attracting a lot of attention from the perspective of fundamental science, and possible interesting applications. In our work we theoretically analyze the eigenstates in a two-excitation domain of an ensemble of two-level atoms that are periodically spaced, and asymmetrically coupled to a guided mode. We found that in a regime when all atoms emit photons in-phase, most eigenstates in such a system can be well-approximated and described through the eigenstates from a single excitation domain, while the rest present a superposition of bound states with two strongly attracting excitations, and states, for which the excitations strongly repel from each other occupying the opposite edges of the system.
Bosonic Hofstadter butterflies in the presence of phonon modes
Authors: Krivosenko Yury , Iorsh Ivan , Shelykh Ivan
Published: November 2021

We have investigated the influence of lattice sites vibrations on bosonic Hofstadter’s butterfly (HB) spectrum for the case of conventional square lattice. Only the pair of specific phonon modes with opposite quasimomenta has been taken into account. The study has shown that HB-type spectra can be substantially modified by the presence of phonons, depending on the ratios of such parameters of the system as site-to-site transition amplitudes, particle-phonon interaction constant, and characteristic vibration frequency.
Non-Huygens transparent metasurfaces based on the novel Hybrid anapole state
Authors: Kuznetsov A V , Canós Valero A
Published: November 2021

In this work we studied the optical properties of the metasurfaces based on silicon nanocylinders experincing hybrid anapole. Our investigation shows the possibility of creating fully invisible metasurfaces consisting of silicon nanocylinders based on the novel state which in their properties can compete with the Huygens’ metasurfaces. These results can be used in various fields of nanophotonics and may have important outcome in the development of various photonic devices.
Up-conversion photoluminescence specificity of a hybrid sponge nanostructures
Authors: Larin Artem , Kurganov Egor , Bruyére Stephanie , Nominé Alexandre , Ageev Eduard , Samusev Anton , Zuev Dmitry
Published: November 2021

Over the past decades, silicon is proved to be as a promising material for the development of devices in the fields of nanophotonics and optoelectronics. However, the material so popular at the current time did not find its application in nanoscale radiation sources due to the indirect bandgap of the semiconductor, which leads to low quantum efficiency. This work represents experimental results on the features of the silicon up-conversion photoluminescence enhanced by the optical resonances of the plasmonic nanosponge. The internal configuration of the nanostructure was confirmed by scanning transmission electron microscopy. The optical characterisation was provided by the dark-field spectroscopy, up-conversion photoluminescence generation and life-time measurements. The such new nanostructure type is promising for the development of nanoscale sources of broadband radiation and other applications of silicon photonics.
Flat-band dark polaritons in two-dimensional chiral-waveguide quantum electrodynamics
Authors: Marques Y. , Shelykh I. A. , Iorsh I. V.
Published: November 2021

We consider a two-dimensional extension of the one-dimensional waveguide quantum electrodynamics and investigate the nature of linear excitations in two-dimensional arrays of qubits (particularly, semiconductor quantum dots) coupled to networks of chiral waveguides. We show that the combined effects of chirality and long-range photon mediated qubit-qubit interactions lead to the emergence of the two-dimensional flat bands in the polaritonic spectrum, corresponding to slow strongly correlated light.
Upconversion photoluminescence of perovskite nanoparticles encapsulated in porous sub-micron spheres supporting Mie resonances.
Authors: Masharin Mikhail , Peltek Oleksii , Talianov Pavel , Zelenkov Lev , Zuyzin Mikhail , Makarov Sergey
Published: November 2021

Currently, halide perovskites are very perspective materials not only for photovoltaics but also for nanophotonic and especially nonlinear optics. These materials have already demonstrated high two-, three- and many- photon absorption coefficients, strong Kerr-nonlinearity, and high-efficient second harmonic generation. Easy and cheap fabrication gives halide perovskites a wide area for scientific research and engineering applications. However, to achieve the stability of perovskites is still a challenging task, which scientific community is working on. In this work, we study a new form of encapsulation of perovskite nanoparticles in sub-micron porous dielectric nanospheres. Due to small pores in such spheres, perovskites are not only protected from external factors, but also are confined in size, which brings several features in the photoluminescence emission. We also show resonant properties of spherical sub-micron particles, which can be used for enhancing upconversion photoluminescence intensity.
Stability of bound states in the continuum in low-contrast photonic structures
Authors: Maslova E. E. , Bogdanov A.A. , Rybin M. V. , Sadrieva Z. F.
Published: November 2021

We consider quality (Q) factor of accidental bound states in the continuum in bilayer resonators consisting of low-index dielectric rods. The dependence of Q factor on the number of periods shows that Q factors increase with the increasing number of rods. We calculated the dependence of the resonator Q factor on the disorder by two methods: analytical (multiple scattering theory) and numerical (finite difference method) and showed that the results are in good agreement. Also, we investigated the dependence of the resonance frequency on disorder.
Creation of complex composites from Metal-Organic Frameworks with pure metal nanoparticles under electronic irradiation
Authors: Mezenov Yuri A. , Bruyere Stéphanie , Milichko Valentin A.
Published: November 2021

Metal-organic frameworks (MOFs) are unique materials with high porosity and flexibility utilized widely in chemistry and physics. However, they could be used as initial materials for creation new types of composites with nanoparticles. The creation of NPs inside MOFs crystals is related with different types of outer stimuli (temperature, light, and electron irradiation). Here we report about a new approach of the creation complex composites from MOFs’ crystals using the electron irradiation of the transmission electron microscope (TEM) as a highly precise method for the growing of different types of Ni and Cu nanoparticles and discuss about the dynamical process of NPs growth using the classical kinetic theory.
3D printed Ku band cylindrical Luneburg lens
Authors: Grigoriev I , Munina I , Zelenchuk D
Published: November 2021

The design of the cylindrical Luneburg lens manufactured by using 3D printing facilities was presented, fabricated and experimentally verified. The two different approaches to lens parameter discretization were applied to lens design and compared. The effective dielectric permittivity of Polylactic Acid (PLA) plastic samples with different infilling percentage were estimated by a resonant method.
Trapping-influenced photoluminescence intensity decay in semiconductor nanoplatelets
Authors: Kurilovich A A , Mantsevich V N , Stevenson K J , Chechkin A V , Palyulin V V
Published: November 2021

We present a diffusion-based simulation model for explanation of long time power-law decay of photoluminescence (PL) emission intensity in semiconductor nanoplatelets. In our model the shape of emission curves is an outcome of interplay of recombination, diffusion and trapping of excitons. At short times the excitons diffuse freely following the normal diffusion behaviour. The emission decay is purely exponential and is defined by recombination. At long times the transition into the subdiffusive motion happens and the emission occurs due to the release of excitons from surface traps. A power-law tail for intensity is a consequence of the release. The crossover from onelimit to another is controlled by diffusion properties. The approach reproduces the properties of experimental curves measured for different nanoplatelet systems.
Angular Goos-Hanchen shift in subwavelength gratings enhanced by surface plasmon resonance
Authors: Petrov N I , Danilov V A , Usievich B A
Published: November 2021

The angular Goos-Hanchen shift dependence on the subwavelength grating parameters and the incident Gaussian beam width is investigated theoretically. High sensitivity of the angular Goos-Hanchen shift to the incident angle of a light beam near the surface plasmon resonance is demonstrated. Splitting of the reflected beam into two angularly separated beams is shown for strongly focused beam incident at the surface plasmon resonance angle.
Theoretical study of surface states excitation in one-dimensional photonic crystal by halide perovskite microstructures
Authors: Popkova A.A. , Safronov K.R. , Markina D.I. , Pushkarev A. , Makarov S.V. , Bessonov V.O. , Fedyanin A.A.
Published: November 2021

In this work we develop the concept of integrated light source based on halide perovskite microwires for Bloch surface waves (BSWs) in one-dimensional photonic crystals. We theoretically study modes supported by a CsPbBr3 microwire placed on the surface of a photonic crystal. The modes with field distribution similar to BSW are observed. We study the coupling of microwire modes with BSWs depending on the geometric parameters of the wire. BSW excitation efficiency exceeding 40% is found for BSW-like modes of microwire. We also examine resonant modes of finite microwire and show that BSW-like modes play a main role in the excitation of BSWs with perovskite radiation. Our research paves the way for the implementation of complete integrated optical setups on the surface of photonic crystals.
Magneto-optical effects in second harmonic generation from W/Co/Pt nanofilms
Authors: Radovskaya V.V. , Mamonov E.A. , Pashen’kin I.Yu. , Gusev N.S. , Murzina T.V.
Published: November 2021

Interfaces between ferromagnetic metals and nonmagnetic specimen attract much attention as they are very important for the formation of magnetic properties of nanostructures. Vice versa, specific magnetic ordering at such interfaces may provide new effects in their optical and nonlinear optical response. In this work we study the magnetization-induced effects in optical second harmonic generation (SHG) in W/Co/Pt-based thin films with the thicknesses of the Co layer of 2 – 10 nm. Besides common odd in magnetization effects in the SHG intensity, we observe additional one that is not expected for homogeneously magnetized ferromagnetic films, which consists in modulation of p-polarized SHG intensity under longitudinal magnetic field application. The phenomenological description of the observed effect is performed in terms of gradient and second-order in magnetization contributions to the SHG polarization, where gradient of magnetization along the normal to the structure plays the key role.
Non-collinear ground state and stable bimerons from four-spin chiral interactions in D3h magnet
Authors: Rakhmanova G R , Osipov A N , Ilin D I , Shushakova I V , Iorsh I V
Published: November 2021

We demonstrate that four-spin interactions in crystals with D3h point group of symmetry can cause a phase transition from a collinear state to a non-collinear magnetic ground state (such as magnetic vortices or magnetic skyrmions), while all anti-symmetric chiral terms are forbidden by symmetry in such crystals. Moreover, D3h point group rather common among two dimensional magnets. Taking into account possible four-spin chiral exchange interactions is important for understanding noncollinear magnetic order in these systems. We also address a possible stabilization of bimerons by the same contribution.
Light propagation and interaction modelling in ring fibre nonlinear microcavities
Authors: Razukov V A , Melnikov L A
Published: November 2021

Usage of the ”Cabaret” explicit-implicit numerical scheme is proposed to model field dynamics both in microcavities and fibre cavities. Two opposite running waves are investigated with a number of the nonlinear effects included in the model, with potential to include more if necessary.
III-V nanowires with quantum dots: MBE growth and properties
Authors: Reznik R R , Kotlyar K P , Gridchin V O , Ilkiv I V , Khrebtov A I , Samsonenko Yu B , Soshnikov I P , Kryzhanovskaya N V , Leandro L , Akopian N , Cirlin G E
Published: November 2021

We demonstrate growth of AlGaAs NWs with GaAs QDs and InP NWs with InAsP QDs on silicon substrates. Results of GaAs QDs optical properties study have shown that these objects are sources of single photons. In case of InP NWs with InAsP QDs, the results showed that ~ 100% of homogeneously oriented NWs were formed with good optical quality of this system on a Si(111). PL spectrum peak near 1.3 μm indicates that such system is promising for optoelectronic devices.
Optical heating of doped semiconductor nanocylinders supporting quasi-BIC modes
Authors: Ryabov Daniil , Pashina Olesia , Zograf George , Makarov Sergey , Petrov Mihail
Published: November 2021

In the recent years, semiconductor and dielectric nanophotonic structures attracted a lot of attention for their resonant optical properties finding applications in thermal tuning and optical heating. Exciting high quality optical modes of both electric and magnetic nature in nanoresonators of high-index materials, one can effectively enhance optical absorption in such structures. Another big advantage of semiconductor materials is the ability to finely control the level of optical losses in visible and near infrared (near-IR) range through varying the doping level. In this work, we show theoretically that by moderate carrier doping of silicon via donors from group V materials one can achieve effective heating of nanoresonators. We show that by tuning the doping level of crystalline silicon supporting high quality non-radiative modes based on quasi bound states in the continuum one can achieve strong heating in near-IR under continuous wave regime illumination. We believe that our finding will pave the way for an efficient semiconductor near-IR all-optical sensors and nanoheaters.
Synthesis of prolate gold nanoparticles for use in plasmon-enhanced overtone near-infrared spectroscopy
Authors: Sapunova A A , Dadadzhanov D R , Dubovik A Y , Baranov M A , Toropov N A , Vartanyan T A
Published: November 2021

Gold nanoparticles were obtained by the method of three-stage growth from a seed solution. Scanning electron microscopy images as well as comparison of extinction spectra to the results of numerical simulations prove the formation of prolate nanoparticles. Such particles with localized plasmon resonance in the NIR region are much-needed for the plasmon-enhanced overtone spectroscopy.
Polarized Raman spectroscopy of GaP nanowires under 5% elastic strain
Authors: Sharov Vladislav , Fedorov Vladimir , Alekseev Prokhor , Mukhin Ivan
Published: November 2021

Optical porperties of highly-strained gallium phosphide nanowires were investigated via polarized Raman spectroscopy. 5% elastic strain was created in individual nanowire lying on nickel substrate by the means of atomic force microscopy. Micro-Raman mapping along the nanowire cross section in parallel and perpendicular polarization was carried out. Strain-induced effects on transverse optical mode position and shape were analyzed. The pronounced splitting of the mode due to high level of strain was observed. It was found that in parallel polarization the mode shape is sensitive to the position of the pumping spot which can be attributed to enhanced light-nanowire coupling effects.
Strong light-matter coupling in topological metasurfaces integrated with transition metal dichalcogenides
Authors: Sinev Ivan , Li Mengyao , Benimetskiy Fedor , Ivanova Tatiana , Kiriushechkina Svetlana , Vakulenko Anton , Guddala Sriram , Krizhanovskii Dmitry , Samusev Anton , Khanikaev Alexander
Published: November 2021

Strong light-matter interactions enable unique nonlinear and quantum phenomena at moderate light intensities. Within the last years, polaritonic metasurfaces emerged as a viable candidate for realization of such regimes. In particular, planar photonic structures integrated with 2D excitonic materials, such as transition metal dichalcogenides (TMD), can support exciton polaritons – half-light half-matter quasiparticles. Here, we explore topological exciton polaritons which are formed in a suitably engineered all-dielectric topological photonic metasurface coupled to TMD monolayers. We experimentally demonstrate the transition of topological charge from photonic to polaritonic bands with the onset of strong coupling regime and confirm the presence of one-way spin-polarized edge topological polaritons. The proposed system constitutes a promising platform for photonic/solid-state interfaces for valleytronics and spintronics.
Laser induced tunable Ge2Sb2Te5 phase-change gratings
Authors: Trofimov Pavel I. , Bessonova Irina G. , Lazarenko Petr I. , Kirilenko Demid A. , Bert Nikolay A. , Kozyukhin Sergey A. , Sinev Ivan S.
Published: November 2021

Periodic photonic nano- and microstructures are routinely used for light manipulation at the nanoscale. However, their fabrication process is demanding in terms of time, cost and facilities. Here we demonstrate a rapid laser-assisted method for fabrication of gratings in Ge2Sb2Te5 (GST) thin films, based on the formation of laser induced periodic surface structures (LIPSS). LIPSS formation mechanisms dependent on the wavelength of the operating laser, lead to high flexibility of the process, producing gratings with tunable period and orientation with respect to the initial laser polarization. The phase-change properties of GST, on the other hand, allows to fabricate phase gratings with strong modulation of refractive index, which are rewritable in nature.
Tungsten disulfide nanoparticles produced by femtosecond laser ablation in water for nanophotonic applications
Authors: Tselikov G I , Popov A A , Ermolaev G A , Syuy A V , Kabashin A V , Arsenin A V , Volkov V S
Published: November 2021

We demonstrate nearly spherical nanoparticles of tungsten disulfide (WS2) produced by femtosecond pulsed laser ablation of bulk target in deionized water. Structural and optical analysis reveals that produced nanospheres preserve the crystalline structure, high refractive index and support strong excitons and Mie resonances in the spectral range 400-700 nm, resulting in enhanced photothermal response probed by Raman spectroscopy.
Comparison of angular-selective metasurfaces as tools for sub-THz single-frequency sensing
Authors: Tumashov M A , del Risco J P , Glybovski S B , Sayanskiy A D , Kuznetsov S A , Baena J D
Published: November 2021

We demonstrate and numerically characterize a set of single-layer metasurfaces based on capacitively-coupled bent metal strips deposited on a thin polypropylene film operating as band-stop filters at 139.1 GHz. Due to a high inter-digital coupling capacitance between neighboring inclusions formed by the strips, the resonance of the metasurface becomes highly sensitive to the incidence angle of a plane wave. At the same time, a narrow-band resonance is achieved by reducing the conductor length along the vertical polarization direction of the incident wave. We propose to use both properties for designing a sensor, which analyses the thickness of a thin slab of a known substance deposited over the structure by tracking the angle at which the minimum of transmission can be measured at a single frequency. We compare three versions of the proposed geometry by numerical calculation of the transmission coefficient depending on both the incidence angle and analyte slab’s thickness. We select the most suitable structure for sensing.
Problems of sub-THz astronomy, radars and telecommunications: development of equipment and methods
Authors: Bubnov Gregory , Gunbina Aleksandra , Kovalev Fedor , Lesnov Ilya , Mineev Kirill , Vdovichev Sergey , Vdovin Vyacheslav
Published: November 2021

Some original results of development methods and equipment for subterahertz astronomy, radars and telecommunications are presented in this paper. There are problems of extremely low sensitivity of receivers, high power transmitters, atmosphere propagation and development of key solid state components for this band: detectors arrays, cooling systems, antennas and so on.
Dielectric metasurface for emission control of magnetic dipole in the near-IR wavelength range
Authors: Yaroshenko Vitaly , Obramenko Marina , Larin Artem , Ageev Eduard , Zuev Dmitry
Published: November 2021

Developing active dielectric systems is in high demand due to growing the internet of things. Such systems can control the optical properties of nanoemitters which leads to an increase in the performance of the telecommunication networks. Here we numerically investigate metasurface consists of all-dielectric erbium-doped silicon nanocylinders. We demonstrate that such a structure can effectively control and enhance 320-folds spontaneous emission in the near-IR wavelength range. The results of this paper can be used for creating new telecommunication systems.
Dielectric nanoresonator for enhancement of 2D material photoluminescence
Authors: Yaroshenko Vitaly , Kustov Pavel , Zuev Dmitry
Published: November 2021

Nowadays the volume of transmitted information exponentially grows and requires the development of new telecommunication systems. Dielectric nanoresonators can be considered as a basic part of such systems to control the emission of the nanoscale source. Here we numerically investigated resonant dielectric nanoresonators for emission enhancements of 2D nanomaterials. We show that the radiative Purcell factor can achieve the value of up to 21 and 12 for the magnetic quadrupole and dipole responses, respectively. Also, we compare the directivity patterns for magnetic dipole and quadrupole resonances. The results obtained in this work can be applied in the development of optical chips and interfaces.