Low-loss Materials Research Articles

Erratum to “Extraction of Stable Complex Permittivity and Permeability of Low-Loss Materials From Transmission/Reflection Measurements” [2021 Art. no. 6003608

Erratum to “Extraction of Stable Complex Permittivity and Permeability of Low-Loss Materials From Transmission/Reflection Measurements” [2021 Art. no. 6003608

Low-Frequency Near-Field Interferometry for Characterization of Lossy Dielectric and an Investigation on Sea Ice

The far-field interferometry is a well-established method of subsurface characterization, and it has traditionally been used to determine the dielectric properties and thickness of very low-loss subsurface materials, whose dimensions are comparable to the operating wavelength. However, this method is not very well suited for dielectrics with losses several orders high and, therefore, cannot be considered as a general method of subsurface characterization. In this article, we introduce a new idea of near-field interferometry, which can be used to characterize higher loss dielectrics with dimensions very low compared with the wavelength. It is shown that, in low frequencies, there is a noticeable variation in the field components with different medium dielectric properties and thickness, and these changes can be detected externally from near-field measurements by varying receiver distance and the operating frequency. The proposed method is tested on a lossy sea ice model in the presence of a horizontal electric dipole, and the variation in field magnitudes is observed for thickness up to 5 m. Since practical sea ice bulks have thicknesses of a similar range, the near-field interferometry appears to be a promising approach to determine sea ice thickness from noninvasive measurements.

Multilayer Structure Technique for Improving Determination of Electromagnetic Properties of Radar Absorbers Based on Two-Layer Method and Flanged Rectangular Waveguide Probe

This paper presents further development of utilization of two-layer method to perform nondestructive electromagnetic properties determination of planar radar absorbers using flanged open-ended rectangular waveguide probe. A multilayer structure of three layers was proposed to improve the measured results of these parameters obtained using two-layer method. These layers were arranged such that the test material is sandwiched between two known low loss materials to provide the needed two independent reflection coefficients necessary to extract them at different conditions of testing. The proposed structure was aimed to decrease the effect of direct backing of test material by metal plate, which influences measurement accuracy if two-layer method is used. The structure permits a suitable electric field interrogation in test material and decreases the influences of both radial and surface waves. FDTD method was adapted for modeling the problem geometry to calculate the reflection coefficients since a probe with finite flange size is used. Measurements were carried out using the proposed technique to determine complex permittivity and complex permeability of several radar absorbers over X-band applications of microwaves. In comparison with both single-layer and two-layer methods results, the measured results of these parameters agreed well with the published data. by companies and literatures.

Multilayer Structure Technique for Improving Determination of Electromagnetic Properties of Radar Absorbers Based on Two-Layer Method and Flanged Rectangular Waveguide Probe

This paper presents further development of utilization of two-layer method to perform nondestructive electromagnetic properties determination of planar radar absorbers using flanged open-ended rectangular waveguide probe. A multilayer structure of three layers was proposed to improve the measured results of these parameters obtained using two-layer method. These layers were arranged such that the test material is sandwiched between two known low loss materials to provide the needed two independent reflection coefficients necessary to extract them at different conditions of testing. The proposed structure was aimed to decrease the effect of direct backing of test material by metal plate, which influences measurement accuracy if two-layer method is used. The structure permits a suitable electric field interrogation in test material and decreases the influences of both radial and surface waves. FDTD method was adapted for modeling the problem geometry to calculate the reflection coefficients since a probe with finite flange size is used. Measurements were carried out using the proposed technique to determine complex permittivity and complex permeability of several radar absorbers over X-band applications of microwaves. In comparison with both single-layer and two-layer methods results, the measured results of these parameters agreed well with the published data. by companies and literatures.

ASSESSMENT OF TECHNICAL STATE AND DESIGN OF RECONSTRUCTION OF THE SMALL BRIDGE OF THE SLOVINSKY SYSTEM

Abstract. In the 1950s and 1960s of the 20th century a lot of one- and two-span bridges with a span of 4-6 m were built on public roads on the territory of the former USSR. The paper describes the features of the design and construction of small four-hinged reinforced concrete bridges on lightweight supports of engineer Slovinsky system. The experience of surveying small bridges shows that in the context of a limited funding, compared to other types of bridges, maintenance and operation of these bridges does not get enough attention. There are relatively low material losses from their destruction and it is possible to restore them fairly easily. Therefore, many of them have a large number of defects and are in a poor physical condition. The purpose of the work is to draw attention of owners to the problems of small bridges using a specific example, as well as to present effective constructive solutions for the reconstruction of a small four-hinge bridge. These design solutions are developed on the basis of the research and development in Lviv National Polytechnic University and include the use of a reinforced concrete cover slab. The slab has been frequently used in other bridge reconstruction projects and proved its technical and economic efficiency in practice. The article gives characteristics of the bridge, the technical state of its structures, the main defects and damages, as well as the characteristics of the stream and its influence on the condition of the bridge. The design solutions for widening and strengthening the small bridge of the Slovinsky system can provide operational performance and consumer properties in accordance with the requirements of the current design standards for new bridges. These standards are able to ensure the service life of the reconstructed bridge.

Polarization-controlled selective excitation of Mie resonances in a dielectric nanoparticle on a coated substrate

Spherical high-index nanoparticles with low material losses support sharp high-$Q$ electric and magnetic resonances and exhibit a number of interesting optical phenomena. Developments in fabrication techniques have enabled further study of their properties and the investigation of related optical effects. After deposition on a substrate, the optical properties of a particle change dramatically due to mutual interaction. Here, we consider a silicon spherical nanoparticle on a dielectric one-layered substrate. At normal incidence of light, the layer thickness controls the contribution of the nanoparticle's electric and magnetic multipoles to the subsequent optical response. We show that changing the polarization of incident light at a specific excitation angle and layer thickness leads to switching between the multipoles. We further observe a related polarization-driven control over the direction of the scattered radiation.

Modelling and simulation of novel liquid‐infiltrated PCF biosensor in Terahertz frequencies

The liquid-infiltrated photonic crystal fibre (LI-PCF) is proposed for guiding terahertz radiation. Geometrical asymmetry is achieved by introducing a large ellipse in the core. By filling the ellipse with liquid cocaine, the optical properties of the photonic crystal fibre (PCF) are theoretically examined using finite element method-based COMSOL multiphysics software. At an operating frequency of 1 THz, the proposed LI-PCF demonstrates a sensitivity of 87.02% and confinement loss in the order of 10 −4 cm −1 . The PCF also demonstrates extremely low effective material loss <0.01 cm −1 , a birefringence of 0.018, large effective mode area of 1.11 × 10 5 µm 2 , a high numerical aperture of 0.45 and near-zero ultra-flattened chromatic dispersion of 1.4351 ± 0.5883 ps/THz/cm. The design simplicity and high sensitivity, strong confinement factor, low material losses and high birefringence of the fibre suggest that the proposed fibre may be convenient for PCF-based cocaine sensing, for application in the security and defence industries.

3D printed re-entrant cavity resonator for complex permittivity measurement of crude oils

This paper presented a microwave resonator-based dielectric metrology technique using a new unified analytical model to extract complex permittivity of low-loss liquid materials. The main design drive of the modified re-entrant cavity is to confine the electric field and therefore enhance the interaction with the material under test while maintaining high quality factor of the cavity. This enables high sensitivity when measuring complex permittivity of low loss materials. The fabrication of the resonator was made easy by using stereo-lithography (SLA) 3D printing. The measured resonance frequency of the fabricated cavity is 2.09 GHz and the quality factor is 5250. The device was first validated using several common solvents. A unified analytical perturbation model based on simulations is developed for the extraction of the complex permittivity. The influence of the dielectric constant on the loss-tangent model has been fully taken into account. Results obtained agree very well with literature values. The device has subsequently been used in the measurement of crude oil samples and the correlation between permittivity measurement and crude oil category has been established.

Hybrid Thermal Treatment Based on Microwaves and Heating Resistance for Composite Materials

Nowadays, it is well known that volumetric heating through microwaves inhibits certain surface properties from being achieved. Similarly, exclusively heating via thermal radiation is neither deep nor homogeneous enough for short periods of time. But combining both approaches can alleviate such issues. In fact, this kind of hybrid heating has been used for many years in real processes for thermal treatment of composite materials. Nonetheless, many questions remain unsettled. In this manuscript, we discuss the modeling and simulation of such a hybrid system, when heating a heterogeneous load composed of a solid core with three concentric spherical shells. The heating sources are given by electromagnetic waves in the microwave range, and by constant thermal radiation over one of the outer hemispheres. Only the core is considered to absorb the energy transported by the electromagnetic waves (high dielectric loss material). Hence, shells are transparent to microwaves (low dielectric loss materials). The thermophysical properties were considered constant with position. For all cases, peak temperature was observed in the geometrical center of the system, as has been shown by experimentation. Furthermore, simulation results revealed that this hybrid heating strategy has a drastic effect on the temperature profiles generated with only microwave, although the surface temperature homogeneity can be improved using an external electrical resistance.

Plasmonic gold-cellulose nanofiber aerogels.

Assembly of plasmonic nanomaterials into a low refractive index medium, such as an aerogel, holds a great promise for optical metamaterials, optical sensors, and photothermal energy converters. However, conventional plasmonic aerogels are opaque and optically isotropic composites, impeding them from being used as low-loss or polarization-dependent optical materials. Here we demonstrate a plasmonic-cellulose nanofiber composite aerogel that comprises of well-dispersed gold nanorods within a cellulose nanofiber network. The cellulose aerogel host is highly transparent owing to the small scattering cross-section of the nanofibers and forms a nematic liquid crystalline medium with strong optical birefringence. We find that the longitudinal surface plasmon resonance peak of gold nanorods shows a dramatic shift when probed for the cellulose aerogel compared with the wet gels. Simulations reveal the shift of surface plasmon resonance peak with gel drying can be attributed to the change of the effective refractive index of the gels. This composite material may provide a platform for three- dimensional plasmonic devices ranging from optical sensors to metamaterials.

Functional Microarray Platform with Self-Assembled Monolayers on 3C-Silicon Carbide.

Currently available bioplatforms such as microarrays and surface plasmon resonators are unable to combine high-throughput multiplexing with label-free detection. As such, emerging microelectromechanical systems (MEMS) and microplasmonics platforms offer the potential for high-resolution, high-throughput label-free sensing of biological and chemical analytes. Therefore, the search for materials capable of combining multiplexing and label-free quantitation is of great significance. Recently, interest in silicon carbide (SiC) as a suitable material in numerous biomedical applications has increased due to its well-explored chemical inertness, mechanical strength, bio- and hemocompatibility, and the presence of carbon that enables the transfer-free growth of graphene. SiC is also multifunctional as both a wide-band-gap semiconductor and an efficient low-loss plasmonics material and thus is ideal for augmenting current biotransducers in biosensors. Additionally, the cubic variant, 3C-SiC, is an extremely promising material for MEMS, being a suitable platform for the easy micromachining of microcantilevers, and as such capable of realizing the potential of real time miniaturized multiplexed assays. The generation of an appropriately functionalized and versatile organic monolayer suitable for the immobilization of biomolecules is therefore critical to explore label-free, multiplexed quantitation of biological interactions on SiC. Herein, we address the use of various silane self-assembled monolayers (SAMs) for the covalent functionalization of monocrystalline 3C-SiC films as a novel platform for the generation of functionalized microarray surfaces using high-throughput glycan arrays as the model system. We also demonstrate the ability to robotically print high throughput arrays on free-standing SiC microstructures. The implementation of a SiC-based label-free glycan array will provide a proof of principle that could be extended to the immobilization of other biomolecules in a similar SiC-based array format, thus making potentially significant advances to the way biological interactions are studied.

Versatile Photonic Entanglement Synthesizer in the Spatial Domain

Multimode entanglement is an essential resource for quantum information in continuous-variable systems. Light-based quantum technologies will arguably not be built upon table-top bulk setups, but will presumably rather resort to integrated optics. Sequential bulk optics-like proposals based on cascaded integrated interferometers are not scalable with the current state-of-the-art low-loss materials used for continuous variables. We analyze the multimode continuous-variable entanglement capabilities of a compact currently-available integrated device without bulk-optics analog: the array of nonlinear waveguides. We theoretically demonstrate that this simple and compact structure, together with a reconfigurable input pump distribution and multimode coherent detection of the output modes, is a versatile entanglement synthesizer in the spatial domain. We exhibit this versatility through analytical and numerically optimized multimode squeezing, entanglement, and cluster state generation in different encodings. Our results re-establish spatial encoding as a contender in the game of continuous-variable quantum information processing.

Suppressing material loss in the visible and near-infrared range for functional nanophotonics using bandgap engineering

All-dielectric nanostructures have recently opened exciting opportunities for functional nanophotonics, owing to their strong optical resonances along with low material loss in the near-infrared range. Pushing these concepts to the visible range is hindered by their larger absorption coefficient, thus encouraging the search for alternative dielectrics for nanophotonics. Here, we employ bandgap engineering to synthesize hydrogenated amorphous Si nanoparticles (a-Si:H NPs) offering ideal features for functional nanophotonics. We observe significant material loss suppression in a-Si:H NPs in the visible range caused by hydrogenation-induced bandgap renormalization, producing strong higher-order resonant modes in single NPs with Q factors up to ~100 in the visible and near-IR range. We also realize highly tunable all-dielectric meta-atoms by coupling a-Si:H NPs to photochromic spiropyran molecules. ~70% reversible all-optical tuning of light scattering at the higher-order resonant mode under a low incident light intensity is demonstrated. Our results promote the development of high-efficiency visible nanophotonic devices.

Molecular‐Scale Strategies to Achieve High Efficiency and Low Efficiency Roll‐off in Simplified Solution‐Processed Organic Light‐Emitting Diodes

AbstractSolution‐processed small‐molecule organic light‐emitting diodes (OLEDs) are regarded as next‐generation flat‐panel displays and solid‐state lighting sources due to low material loss and a simple device fabrication process. However, they still suffer from low device efficiency and severe efficiency roll‐off. Here, molecular‐scale strategies are proposed to achieve highly efficient solution‐processed small‐molecule OLEDs with reduced efficiency roll‐off. By combining experiments with ab initio and molecular dynamics simulations, it is shown that an acetylacetonate group in a phosphorescent dopants lowers the dipole moment and molecular interaction energy of dopants, reducing dopant aggregation and increasing charge carrier transport. Furthermore, a charge‐balance assistant molecule is incorporated in the mixed‐host emitting layer to increase the balance of charge carrier transport and to broaden the exciton recombination zone in the center of the emitting layer. The resulting OLEDs have a current efficiency (CE) of 103.7 cd A−1, which is the highest yet reported in solution‐processed OLEDs, and low efficiency roll‐off (CE = 99.68 cd A−1 at a luminance LEL = 100 cd m−2, and CE = 75.00 cd A−1 at LEL = 1000 cd m−2) even with the simplified device architecture. It is expected that this strategy will advance the feasibility of commercialization of low‐cost high‐efficiency OLEDs.

Низькотемпературне дослідження втрат електромагнітної енергії в слабопоглинаючих матеріалах у діапазоні частот 110…140 ГГц

Низькотемпературне дослідження втрат електромагнітної енергії в слабопоглинаючих матеріалах у діапазоні частот 110…140 ГГц

Materials loss measurements using superconducting microwave resonators.

The performance of superconducting circuits for quantum computing is limited by materials losses. In particular, coherence times are typically bounded by two-level system (TLS) losses at single photon powers and millikelvin temperatures. The identification of low loss fabrication techniques, materials, and thin film dielectrics is critical to achieving scalable architectures for superconducting quantum computing. Superconducting microwave resonators provide a convenient qubit proxy for assessing performance and studying TLS loss and other mechanisms relevant to superconducting circuits such as non-equilibrium quasiparticles and magnetic flux vortices. In this review article, we provide an overview of considerations for designing accurate resonator experiments to characterize loss, including applicable types of losses, cryogenic setup, device design, and methods for extracting material and interface losses, summarizing techniques that have been evolving for over two decades. Results from measurements of a wide variety of materials and processes are also summarized. Finally, we present recommendations for the reporting of loss data from superconducting microwave resonators to facilitate materials comparisons across the field.

Material Measurements Using VNA-Based Material Characterization Kits Subject to Thru-Reflect-Line Calibration

This article presents a study of different calibration techniques for vector network analyzer -based material measurements using commercially available material characterization kits (MCKs). Such MCKs are designed for fast broadband material characterization at millimeter-wave and terahertz frequencies and are based on gated-reflect-line calibration for removal of errors associated with the fixture. In this article, we have applied thru-reflect-line (TRL) calibration to the MCKs, yielding robust S -parameters that are used to calculate the relative permittivity and loss tangent of materials. Two different types of line standards, i.e., custom machined corrugated lines and air lines (a quarter-wave air gap between the ports of the MCKs), were employed to produce the desired phase shift. Both types of standard produced similar results. These investigations were carried out on three types of low-loss dielectric material, using MCKs operating at two selected waveguides bands within the range 140–750 GHz. The same samples were measured using time-domain spectroscopy (TDS) for comparison. The extracted relative permittivities and loss tangents using MCKs with TRL calibration and TDS are compared against literature values. Good agreement is achieved.

Advanced Low Df Dry film Build-up Material on Glass panel for 5G application

Abstract This paper describes the demonstration of a low loss substrate (laminated glass) for high-frequency transmission using a dry film build-up material with low loss tangent (Df). This paper also evaluates filter characteristics and dielectric characteristics of the substrate in the mm-Wave band. The advanced low loss dry film build-up material was newly developed, and applicable to high frequency transmission. This material has a Df of 0.0025 at 10 GHz and also exhibits excellent adhesion and electrical reliability required for advanced dielectric materials. In addition, glass was used as a core material in this paper because of its excellent signal transmission characteristics compared to silicon wafers or organic substrates. To demonstrate the benefit of low loss materials for high frequency transmission, passive components for high frequency filter substrates were fabricated using - 6-inch square thin (0.2mm) glass panel with various build-up materials (Material A with a Df of 0.0025, and Material B with a Df 0.0042 at 10 GHz) laminated. Copper wiring patterns on the dielectric layers were fabricated by a semi-additive process (SAP). Circuit patterns with low pass filters and band pass filters were also fabricated. First, transmission characteristics and characteristic impedances were measured to check the electrical performance. The measured lowest transmission loss of &amp;lt; 1.43 dB at 39 GHz were achieved when Material A was applied as the build-up material. Second, biased-highly accelerated stress test (bHAST) was conducted to evaluate the reliability performance of the substrates with two build-up materials, Material A and a conventional material. The test condition was based on the JEDEC level 2 standard. The substrate with Material A retained good insulation properties over 300 hours of bHAST treatment, demonstrating its excellent insulating performance. In summary, Material A has been shown in this paper to exhibit reduced transmission loss in high-frequency filter substrates at millimeter wave frequencies.

Miniaturizing nanoantennas with hybrid photonic-plasmonic modes for improved metasurfaces.

The increasing interest in manipulating light on scales much smaller than its wavelength has driven intensive research on designing high efficiency optical antennas for near and far field applications. In particular, such nanoantennas serve as the main building block of metasurfaces, which were identified as an emerging technology for their capability in constructing versatile optical and electromagnetic devices. Hence, reducing the antennas' dimensions without compromising on their scattering efficiency is of utmost importance. In this Letter, we show that nanoantennas carved from hybrid plasmonic-dielectric waveguides preserve the unique properties of the hybrid modes, showing stronger confinement and better tunability at a relatively low loss, emanating from the coupling between the dielectric and plasmonic modes. This enables a design of high performance ultrasmall antennas that outperform dielectric and plasmonic nanoantennas at similar dimensions. We demonstrate this capability by simulating the performance of metasurfaces made of ultrasmall hybrid nanoantennas, proven to be superior over their dielectric and plasmonic counterparts. Using such hybrid nanoantennas as unit-cells in metasurfaces holds a great promise for designing new tunable, multifunctional, and low-loss nano-optical materials and applications.

Spider web ultrasensitive terahertz photonic crystal fiber for chemical sensing

A photonic crystal fiber (PCF) made up of a spider-web such as cladding and an octagonal core is proposed for sensing applications. Three widely used industrial liquids and/or by-products, namely, water, acetic acid, and glycerol, have been investigated using the full vector finite element method. Extremely high sensitivities of 99.5%, 99.7%, and 99.9% were achieved at 4.5 THz for water, acetic acid, and glycerol, respectively. In addition to the sensitivity, extremely low effective material losses of 0.0004138, 0.000306, and 0.000113 cm − 1 were achieved for water, acetic acid, and glycerol, respectively. Other parameters such as confinement loss, nonlinearity, and dispersion equally showed well-enhanced results compared to previous related works. The excellent sensing performance and ultralow confinement loss of this proposed PCF chemical-sensor make it a worthy candidate for use in many industrial sectors.