A concept of "materials" diffraction and imaging beamline for SKIF: Siberian circular photon source.

Over the next decade, the extremely brilliant fourth generation synchrotron radiation sources are set to become a key driving force in materials characterization and technology development. In this study, we present a conceptual design of a versatile "Materia" diffraction and imaging beamline for a low-emittance synchrotron radiation facility. The beamline was optimized for operation with three main principal delivery regimes: parallel collimated beam ∼1 mm beam size, micro-focus regime with ∼10 μm beam spot size on the sample, and nano-focus regime with <100 nm focus.

Fiber Optic Impact Location System Based on a Tracking Tandem Low-Coherence Interferometer.

This study proposes a method for detecting small-length fluctuations for fiber-optic sensors (FOS). The method is based on a tracking tandem low-coherence interferometer and enables the ability to compensate for temperature and deformation drifts in FOS. As a result, the constant high sensitivity of FOS over a wide frequency range is guaranteed.

Observation of collective excitation of surface plasmon resonances in large Josephson junction arrays.

Josephson junctions can be used as sources of microwave radiation. However, synchronization of many junctions is required for achieving a coherent amplification of the emitted power. In this work we present an experimental study of large arrays containing up to one thousand Nb/Nb Si /Nb junctions.

Coherent amplification of radiation from two phase-locked Josephson junction arrays.

We analyze experimentally and theoretically mutual phase locking and electromagnetic interaction between two linear arrays with a large number of Josephson junctions. Arrays with different separation, either on the same chip or on two separate substrates are studied. We observe a large coherent gain, up to a factor of three, of emitted power from two simultaneously biased arrays, compared to the sum of powers from two individually biased arrays.

Balancing the Number of Quantum Wells in HgCdTe/CdHgTe Heterostructures for Mid-Infrared Lasing.

HgCdTe-based heterostructures with quantum wells (QWs) are a promising material for semiconductor lasers in the atmospheric transparency window (3-5 μm) thanks to the possibility of suppressing Auger recombination due to the no-parabolic law of carrier dispersion. In this work, we analyze the thresholds of stimulated emission (SE) under optical pumping from heterostructures with a different number of QWs in the active region of the structure. Total losses in structures are determined from the comparison of thresholds for the different number of QWs in the active region.

Sensing nitriles with THz spectroscopy of urine vapours from cancers patients subject to chemotherapy.

A THz nonstationary high-resolution spectrometer based on semiconductor superlattice multipliers is applied to investigate the dynamics of urine composition for cancer patients treated with chemotherapy. The molecular urine composition of healthy volunteers and cancer patients was compared and contrasted. We have found a set of nitriles that either appeared after chemotherapy or increased in content, which are expected as a result of bio-chemical damage to the liver.

Millimeter-Wave Imaging System Based on Direct-Conversion Focal-Plane Array Receiver.

A new approach to millimeter-wave imaging was suggested and experimentally studied. This approach can be considered as the evolution of the well-established focal-plane array (FPA) millimeter-wave imaging. The significant difference is the use of a direct-conversion array receiver, instead of the direct-detection array receiver, along with the frequency-modulated continuous-wave (FMCW) radar technique.

Efficiency of electron cooling in cold-electron bolometers with traps.

Electron on-chip cooling from the base temperature of 300 mK is very important for highly sensitive detectors operating in space due to problems of dilution fridges at low gravity. Electron cooling is also important for ground-based telescopes equipped with He cryostats being able to function at any operating angle. This work is aimed at the investigation of electron cooling in the low-temperature range.

Numerical modeling of a multi-frequency receiving system based on an array of dipole antennas for LSPE-SWIPE.

Here we present the results of a numerical modeling of mode composition in the constriction of the Large Scale Polarization Explorer-Short-Wavelength Instrument for the Polarization Explorer (LSPE-SWIPE) back-to-back horn. These results are used for calculating the frequency response of arrays of planar dipole antennas with cold-electron bolometers for 145, 210, and 240 GHz frequencies. For the main frequency channel (i.

Interaction of Ge(Si) Self-Assembled Nanoislands with Different Modes of Two-Dimensional Photonic Crystal.

The interaction of Ge(Si)/SOI self-assembled nanoislands with modes of photonic crystal slabs (PCS) with a hexagonal lattice is studied in detail. Appropriate selection of the PCS parameters and conditions for collecting the photoluminescence (PL) signal allowed to distinguish the PCS modes of different physical nature, particularly the radiative modes and modes associated to the bound states in the continuum (BIC). It is shown that the radiative modes with relatively low Q-factors could provide a increase greater than an order of magnitude in the integrated PL intensity in the wavelength range of 1.

Stimulated Emission up to 2.75 µm from HgCdTe/CdHgTe QW Structure at Room Temperature.

Heterostructures with thin Hg(Cd)Te/CdHgTe quantum wells (QWs) are attractive for the development of mid-infrared interband lasers. Of particular interest are room-temperature operating emitters for the short-wavelength infrared range (SWIR, typically defined as 1.7-3 μm).

Approaching microwave photon sensitivity with Al Josephson junctions.

Here, we experimentally test the applicability of an aluminium Josephson junction of a few micrometers size as a single photon counter in the microwave frequency range. We have measured the switching from the superconducting to the resistive state through the absorption of 10 GHz photons. The dependence of the switching probability on the signal power suggests that the switching is initiated by the simultaneous absorption of three and more photons, with a dark count time above 0.

Optical Properties and Upconversion Luminescence of BaTiO Xerogel Structures Doped with Erbium and Ytterbium.

Erbium upconversion (UC) photoluminescence (PL) from sol-gel derived barium titanate (BaTiO:Er) xerogel structures fabricated on silicon, glass or fused silica substrates has been studied. Under continuous-wave excitation at 980 nm and nanosecond pulsed excitation at 980 and 1540 nm, the fabricated structures demonstrate room temperature PL with several bands at 410, 523, 546, 658, 800 and 830 nm, corresponding to the H → I, H → I, S → I, F→ I and I→ I transitions of Er ions. The intensity of erbium UC PL increases when an additional macroporous layer of strontium titanate is used beneath the BaTiO xerogel layer.

A volume plasmon blueshift in thin silicon films embedded within Be/Si periodic multilayer mirrors.

Microstructural properties of the beryllium (Be) and silicon (Si) in periodic multilayer mirrors Be/Si with the variation of film thickness were comprehensively determined by Raman scattering. For the thinner films, the structure of Be evolved in the amorphous phase, and it was transformed into the polycrystalline phase for thicker films. The Si films in the periodic structure were condensed into the amorphous phase.

Influence of Temperature Parameters on Morphological Characteristics of Plasma Deposited Zinc Oxide Nanoparticles.

Zinc oxide nanoparticles were obtained by plasma-enhanced chemical vapor deposition (PECVD) under optical emission spectrometry control from elemental high-purity zinc in a zinc-oxygen-hydrogen plasma-forming gas mixture with varying deposition parameters: a zinc source temperature, and a reactor temperature in a deposition zone. The size and morphological parameters of the zinc oxide nanopowders, structural properties, and homogeneity were studied. The study was carried out with use of methods such as scanning electron microscopy, X-ray structural analysis, and Raman spectroscopy, as well as statistical methods for processing and analyzing experimental data.

A broadband detector based on series YBCO grain boundary Josephson junctions.

Modeling of a broadband receiving system based on a meander series of Josephson YBaCuO grain boundary junctions integrated into a log-periodic antenna was carried out. The electromagnetic properties of the system, namely amplitude-frequency characteristic, beam pattern, and fraction of the absorbed power in each Josephson junction were investigated. Based on the obtained results, a numerical simulation of one-dimensional arrays was carried out.

Tuning Exchange Coupling in a New Family of Nanocrystal-Based Granular Multiferroics Using an Applied Electric Field.

In this work, we demonstrate an experimental realization of a granular multiferroic composite, where the magnetic state of a nanocrystal array is modified by tuning the interparticle exchange coupling using an applied electric field. Previous theoretical models of a granular multiferroic composite predicted a unique magnetoelectric coupling mechanism, in which the magnetic spins of the ensemble are governed by interparticle exchange. The extent of these exchange interactions can be controlled by varying the local dielectric environment between grains.

Graphene-based plasmonic metamaterial for terahertz laser transistors.

This paper reviews recent advances in the research and development of graphene-based plasmonic metamaterials for terahertz (THz) laser transistors. The authors' theoretical discovery on THz laser transistors in 2007 was realized as a distributed-feedback dual-gate graphene-channel field-effect transistor (DFB-DG-GFET) in 2018, demonstrating ∼0.1 µW single-mode emission at 5.

Infrared stimulated emission with an ultralow threshold from low-dislocation-density InN films grown on a vicinal GaN substrate.

Near-infrared stimulated emission from a high-quality InN layer under optical pumping was observed with a threshold excitation power density of 0.3 and 4 kW cm at T = 8 and 77 K, respectively. To achieve such a low threshold power density, vicinal GaN substrates were used to reduce the edge-component threading dislocation (ETD) density of the InN film.

Nonmonotonous temperature dependence of Shapiro steps in YBCO grain boundary junctions.

The amplitudes of the first Shapiro steps for an external signal with frequencies of 72 and 265 GHz are measured as function of the temperature from 20 to 80 K for a 6 μm Josephson grain boundary junction fabricated by YBaCuO film deposition on an yttria-stabilized zirconia bicrystal substrate. Non-monotonic dependences of step heights for different external signal frequencies were found in the limit of a weak driving signal, with the maxima occurring at different points as function of the temperature. The step heights are in agreement with the calculations based on the resistively-capacitively shunted junction model and Bessel theory.

Wideband MOEMS for the Calibration of Optical Readout Systems.

The paper proposes a technology based on UV-LIGA process for microoptoelectromechanical systems (MOEMS) manufacturing. We used the original combination of materials and technological steps, in which any of the materials does not enter chemical reactions with each other, while all of them are weakly sensitive to the effects of oxygen plasma. This made it suitable for long-term etching in the oxygen plasma at low discharge power with the complete preservation of the original geometry, including small parts.

Dynamic Spin-Triplet Order Induced by Alternating Electric Fields in Superconductor-Ferromagnet-Superconductor Josephson Junctions.

Dynamic states offer extended possibilities to control the properties of quantum matter. Recent efforts are focused on studying the ordered states which appear exclusively under the time-dependent drives. Here, we demonstrate a class of systems which feature dynamic spin-triplet superconducting order stimulated by the alternating electric field.