Transmission Measurements Research Articles

Eco-friendly carbon dots induced thermally stable vertical alignment in planar anchored nematic liquid crystal

We report the induction of thermally stable vertical alignment of nematic liquid crystal, 4-cyano-4′-pentylbiphenyl (5CB), in a planar anchored cell by doping with eco-friendly carbon dots (CDs, diameter ∼7–8 nm), investigated through thermal, optical, electro-optical and dielectric spectroscopic techniques. Cross-polarized optical textures and voltage-dependent optical transmission measurements demonstrate the induction of vertical alignment of CDs-5CB composites with concentration of CDs (≥0.3 wt%) in planar anchored sample cells at room temperature. Moreover, the frequency-bias-concentration dependent dielectric studies done also confirms the induced vertical alignment. For instance, the relative dielectric permittivity measured on CDs-5CB composites (CDs ≥ 0.3 wt%) in planar anchored sample cells at bias voltage of 0 V and 30 V DC are almost equal and the presence of a short axis molecular relaxation at 0 V confirms the induced vertical alignment. The concentration and bias dependence of short axis molecular relaxation frequency are also discussed. It appears that CDs are able to align 5CB molecules vertically at the substrate by overcoming the pre-existing planar anchoring. Such induced alignment would propagate through the bulk of sample cell because of the coherence length of nematic liquid crystal molecules and eventually the whole sample obtains vertical alignment. We anticipate the great utility of these composites in the production of eco-friendly liquid crystal displays and other photonic devices, sensors, etc.

A Regression Approach to Model Refractive Index Measurements of Novel 3D Printable Photocurable Resins for Micro-Optofluidic Applications.

In this work, a quadratic polynomial regression model was developed to aid practitioners in the determination of the refractive index value of transparent 3D printable photocurable resins usable for micro-optofluidic applications. The model was experimentally determined by correlating empirical optical transmission measurements (the dependent variable) to known refractive index values (the independent variable) of photocurable materials used in optics, thus obtaining a related regression equation. In detail, a novel, simple, and cost-effective experimental setup is proposed in this study for the first time for collecting the transmission measurements of smooth 3D printed samples (roughness ranging between 0.04 and 2 μm). The model was further used to determine the unknown refractive index value of novel photocurable resins applicable in vat photopolymerization (VP) 3D printing techniques for manufacturing micro-optofluidic (MoF) devices. In the end, this study proved how knowledge of this parameter allowed us to compare and interpret collected empirical optical data from microfluidic devices made of more traditional materials, i.e., Poly(dimethylsiloxane) (PDMS), up to novel 3D printable photocurable resins suitable for biological and biomedical applications. Thus, the developed model also provides a quick method to evaluate the suitability of novel 3D printable resins for MoF device fabrication within a well-defined range of refractive index values (1.56; 1.70).

Lanthanide-doped glass light guides with bright luminance in the green spectral range

Dy3+ and Tb3+ single- and double-doped barium borate glasses are investigated for their luminescence properties. Their potential as luminescent light guide is evaluated on the basis of ray-tracing simulations. Transmission, photoluminescence, and quantum efficiency measurements serve as input data. The luminous flux at the end of the light guide depends significantly on its length as well as on the surface properties. The best results are obtained for light guides with the side faces coated with a 100% reflecting mirror and a rough output face with Lambertian scattering characteristics. For an excitation wavelength of 452 nm, the color impression at the end of a Dy3+/Tb3+ double-doped light guide shifts from blue for very short light guides via white for medium-size light guides to green-yellowish for relatively long light guides.

Characterization of ZnO, Ga-Doped ZnO, and Nd-Ga-Doped ZnO Thin Films Synthesized by Radiofrequency Magnetron Sputtering

Here is described the influence of deposition parameters of ZnO thin films doped with Ga and co-doped with (Ga + Nd) upon the structural, morphological, optical and electrical properties. The transparent conductive thin films were fabricated by radiofrequency (RF) magnetron sputtering using a power of 100 W and a deposition distance of 6 cm. The deposition was performed on glass substrates heated at 150 °C with a time deposition of 90 min. The influence of doping upon the structure of thin films was analyzed by x-ray diffraction (XRD). Optical transmission measurements showed an 85% transparency in the visible range for the undoped ZnO films and the transparency of these films decreased when the dopants were added. Micro-structural analysis obtained by atomic force microscopy (AFM) evidenced that the type of doping modify the microstructure of thin films. Raman and resistivity measurements emphasize the successful incorporation of dopants into the ZnO host material.

Boron-containing plastic composites as neutron shielding material for additive manufacturing processes

A study of samples of shielding materials which exploit plastic as the basis of neutron absorbing composite with 25%–37% weight boron-containing powder has been provided. Composite samples were prepared by fused filament fabrication (FFF). Acrylonitrile butadiene styrene (ABS) and polyethylene terephthalate glycol (PETG) plastics were used as the polymer matrix material, while boron nitride powder and amorphous boron powder were used as boron-containing fillers.According to measurements of the neutron transmission on the monochromatic beam of the IR-8 reactor (main monochromatic neutron beam line - 2.4 Å), the use of boron as a filler in the plastic provides a decrease in the penetration depth of neutrons by 56%–78%: from 3.0 mm for a sample of plastic without filler to 0.65 mm for a sample with amorphous boron powder.Tensile and bending mechanical tests showed that the addition of boron-containing powder leads to development of brittleness of composite materials. The boron-containing samples experienced a 40%–55% of strength decrease and the failure of samples occurred without plastic deformation, while in ABS and PETG samples the plastic deformation takes up a significant portion of the test diagram.

The Wrinkles Characterization in GFRP Composites by Infrared Active Thermography.

An experimental study has been carried out to assess the effectiveness of infrared thermography in wrinkle detection in composite GFRP (Glass Fiber Reinforced Plastic) structures by infrared active thermography. Wrinkles in composite GFRP plates with different weave patterns (twill and satin) have been manufactured with the use of the vacuum bagging method. The different localization of defects in laminates has been taken into account. Transmission and reflection measurement techniques of active thermography have been verified and compared. The section of a turbine blade with a vertical axis of rotation containing post-manufacturing wrinkles has been prepared to verify active thermography measurement techniques in the real structure. In the turbine blade section, the influence of a gelcoat surface on the effectiveness of thermography damage detection has also been taken into account. Straightforward thermal parameters applied in structural health monitoring systems allow an effective damage detection method to be built. The transmission IRT setup allows not only for damage detection and localization in composite structures but also for accurate damage identification. The reflection IRT setup is convenient for damage detection systems coupled with nondestructive testing software. In considered cases, the type of fabric weave has negligible influence on the quality of damage detection results.

Monte Carlo characterization of Si ring modulator PAM-4 eye diagram performance

The eye diagram performance of the Si ring modulator (RM) is Monte Carlo characterized with the RM equivalent circuit model. Inter-die statistical distributions of Si-RM model parameters are determined from simple RM optical transmission and electrical reflection coefficient measurement, and the correlated model parameter sets are randomly generated for Monte Carlo simulation of 40-Gbps 4-level pulse AM (PAM-4) eye diagrams within simulation program with IC emphasis. From the resulting Monte Carlo simulated eye diagrams, the yield for the Si RMs that satisfy optical modulation amplitude and the ratio of level mismatch requirements can be corroborated with measurement. With these, the eye diagrams of Si electronic-photonic integrated PAM-4 transmitters with RMs and driver electronics are Monte Carlo characterized. This approach allows the extension of the standard Si IC characterization technique to the electronic-photonic ICs and can produce better-performing solutions with better yields in the design stage.

The intensity enhancement of transmission small angle x-ray scattering from nanostructures with a high aspect ratio

Transmission small angle x-ray scattering (tSAXS) has been developed as a metrology for the critical dimension (CD) measurements to facilitate integrated circuit (IC) chip fabrications. Synchrotron x-ray sources were used for their high brilliance and a wavelength less than one tenth of a nanometer was chosen for its high penetration power to enable transmission measurements through a silicon wafer with a nominal thickness of 0.7 mm. A major hold back preventing tSAXS from reaching wide applications in IC fabrication is the lack of high brilliance laboratory-based x-ray sources. Within the last few years, even without any major breakthrough in x-ray source technology, this tSAXS metrology has finally been used for 3D NAND and DRAM, i.e., memory chips with tall or high aspect ratio (HAR) architectures. The scattering intensities from HAR structures will be discussed quantitatively in terms of the sample height and the effective longitudinal coherence length of the incident x-ray.

Angle-Dependent Ultrasonic Wave Reflection for Estimating High-Resolution Elastic Properties of Complex Rock Samples

Due to depositional, diagenetic, and structural processes, reservoir rocks are rarely homogeneous, often exhibiting significant short-range variations in elastic properties. Such spatial variability can have measurable effects on macroscopic mechanical properties for drilling and fluid production operations. We describe a new laboratory method for the acquisition of ultrasonic angle-dependent measurements of reflected waves that delivers high-resolution, continuous descriptions of P- and S-wave velocity along the surface of the rock sample. Reflection coefficient vs. incidence angle is the main source of information about rock elastic properties. The acquired measurements are matched to numerical simulations to estimate P- and S-wave velocity and density of the porous sample and their variations within the rock specimen, hence providing continuous descriptions of sample complexity. Data collected from various locations on the rock specimen are subsequently used to construct two-dimensional (2D) models of elastic properties along the surface of the rock sample. P- and S-wave velocities estimated with this method agree well with acoustic transmission measurements for most homogeneous rocks. The spatial resolution of the method is limited by receiver size, measurement frequency, and incidence angle. At high incidence angles, the surface area sensitive to the measurements increases, and consequently, the spatial resolution of the corresponding reflection coefficient decreases across neighboring rock features.

Reliability of VO textsubscript 2-Based mmWave Switches Under 100 Million Thermal Cycles

We report the lifetime investigations of the reversible phase transition vanadium dioxide (VO2) thin film switches integrated with coplanar waveguide (CPW) under fast and direct thermal cycling. We observe that after 100 million thermal cycles, there is no degradation in the performance of VO2 shunt switches operating at 35 – 45 GHz. S11 reflection coefficient as well as S21 transmission measurements (verified independently at both activated and inactivated states) show no statistical difference in port-to-port coupling of the VO2 switch as a function of a cycle number. This study is enabled by the integration of Joule heaters on chip at a close proximity to a shunt VO2 switch and a metallic CPW transmission line. Full-wave electromagnetic and multiphysics electrothermal finite element simulations are conducted to analyze the feasibility of the CPW design and the required time and power for thermal cycling. On-wafer mmWave measurements are carried out on the test vehicle after each thermal cycling phase.

Characterization of a half-wave plate for cosmic microwave background circular polarization measurement with POLARBEAR.

A half-wave plate (HWP) is often used as a modulator to suppress systematic error in the measurements of cosmic microwave background (CMB) polarization. A HWP can also be used to measure circular polarization (CP) through its optical leakage from CP to linear polarization. The CP of the CMB is predicted from various sources, such as interactions in the Universe and extension of the standard model. Interaction with supernova remnants of population III stars is one of the brightest CP sources. Thus, the observation of the CP of CMB is a new tool for searching for population III stars. In this paper, we demonstrate the improved measurement of the leakage coefficient using the transmission measurement of an actual HWP in the laboratory. We measured the transmittance of linearly polarized light through the HWP used in Polarbear in the frequency range of 120-160GHz. We evaluate the properties of the HWP by fitting the data with a physical model using the Markov Chain Monte Carlo method. We then estimate the band-averaged CP leakage coefficient using the physical model. We find that the leakage coefficient strongly depends on the spectra of CP sources. We thus calculate the maximum fractional leakage coefficient from CP to linear polarization as 0.133 ± 0.009 in the Rayleigh-Jeans spectrum. The nonzero value shows that Polarbear has a sensitivity to CP. Additionally, because we use the bandpass of detectors installed in the telescope to calculate the band-averaged values, we also consider systematic effects in the experiment.

Combining Monte Carlo simulation and experimental data for determining the density of polymer materials in gamma scattering and gamma transmission measurements

Combining Monte Carlo simulation and experimental data for determining the density of polymer materials in gamma scattering and gamma transmission measurements

Nonlinear Interferometry for Quantum-Enhanced Measurements of Multiphoton Absorption.

Multiphoton absorption is of vital importance in many spectroscopic, microscopic, or lithographic applications. However, given that it is an inherently weak process, the detection of multiphoton absorption signals typically requires large field intensities, hindering its applicability in many practical situations. In this Letter, we show that placing a multiphoton absorbent inside an imbalanced nonlinear interferometer can enhance the precision of multiphoton cross section estimation with respect to strategies based on photon-number measurements using coherent or even squeezed light directly transmitted through the medium. In particular, the power scaling of the sensitivity with photon flux can be increased by 1 order compared with transmission measurements of the sample with coherent light, such that the measurement precision at any given intensity can be greatly enhanced. Furthermore, we show that this enhanced measurement precision is robust against experimental imperfections leading to photon losses, which usually tend to degrade the detection sensitivity. We trace the origin of this enhancement to an optimal degree of squeezing which has to be generated in a nonlinear SU(1,1) interferometer.

Metakaolin‐based geopolymer concretes for nuclear protection: On the perspective of physicochemical, durability, and microstructure

AbstractAs a striking contribution of metakaolin to geopolymer concretes, the varying contents of metakaolin with quartz powder are included the mixtures with ground granulated blast furnace slag, and quartz sand to observe the mechanical, physical, transport, microstructure, and nuclear protection parameters of the samples, within this study. The geopolymer concrete samples are tested for the mechanical transport and physical properties depending on the curing time, curing temperature, and the raw/by‐product material type. The results show that the samples containing the most metakaolin performed well with a 24‐h compressive strength of 131.78 MPa. Increasing the curing temperature and curing time affected both mechanical, physical and transport properties. In addition, the microstructure of the samples was analyzed by scanning electron microscopy, x‐ray diffraction, and Fourier transform infrared spectroscopy. Moreover, the effect of increasing metakaolin reinforcement on the nuclear protection capacity of the produced geopolymer concretes with experimental gamma transmission and neutron dose measurements was investigated. The M3 sample with high content of both metakaolin and granulated blast‐furnace slag showed the highest resistance to gamma photons in the energy range of 0.081–0.383 MeV. The produced geopolymer samples absorbed almost 40% of the fast neutrons with 4.5 MeV energy. Neutron removal cross sections of the produced geopolymer concretes are in the range of 0.0952–0.0949 cm−1 and are larger than those of B4C, graphite, and boric acid. The findings of this study revealed that the addition of metakaolin improved the mechanical, nuclear shielding and structural properties of geopolymer concretes.

Structural Health Monitoring of Adhesively Bonded Pipe-to-Socket Joints by Integration of Polymer Optical Fibers and Their Load-Dependent Transmission Properties

Adhesively bonded pipe-to-socket joints are used in numerous industrial applications. One example is in the transport of media, e.g., in the gas industry or in structural joints for such sectors as construction, wind energy, and the vehicle industry. To monitor such load-transmitting bonded joints, this study investigates a method based on the integration of polymer optical fibers into the adhesive layer. Previous methods for monitoring the condition of pipes, such as acoustic or ultrasonic methods or the use of glass fiber optic-based sensors (FBG or OTDR), are very complex in methodology and require cost-intensive (opto-) electronic devices to generate and evaluate the sensor signals; they are therefore unsuitable for large-scale use. The method investigated in this paper is based on the measurement of integral optical transmission with a simple photodiode under increasing mechanical stress. When tried at coupon level (single-lap joint), the light coupling was varied to obtain a significant load-dependent sensor signal. Based on an angle-selective coupling of 30° to the fiber axis, a drop of 4% of the optically transmitted light power by a load of 8 N/mm2 can be detected for the adhesively bonded pipe-to-socket joint with the structural adhesive Scotch Weld DP810 (2C acrylate).

Harmonic radiation contribution and X-ray transmission at the Small Quantum Systems instrument of European XFEL.

Transmission measurements of the soft X-ray beamline to the Small Quantum Systems (SQS) scientific instrument at the SASE3 undulator of European XFEL are presented. Measurements are reported for a wide range of photon energies (650 eV to 2400 eV), using X-ray gas monitors as well as a bolometric radiometer. The results are in good agreement with simulations for the beam transport and show a transmission of up to 80% over the whole photon energy range. The contribution of second- and third-harmonic radiation of the soft X-ray undulator is determined at selected photon energies by performing transmission measurements using a gas absorber to provide variable attenuation of the incoming photon flux. A comparison of the results with semi-analytic calculations for the generation of free-electron laser pulses in the SASE3 undulator reveals an influence of apertures along the beam transport on the exact harmonic content to be accounted for at the experiment. The second-harmonic content is measured to be in the range of 0.1% to 0.3%, while the third-harmonic contributed a few percent to the SASE3 emission. For experiments at the SQS instrument, these numbers can be reduced through specific selections of the mirror reflection angles.

Fundamental Investigations of Propagation through the Land–Air–Water Interface in a Controlled Littoral Environment

ABSTRACT Interpreting signals from mechanical waves that cross material media boundaries is challenging due to the historical development of instrumentation suitable to study waves in each distinct medium, leading to discrepancies in boundary and adjacent media descriptions and governing physics related to each media. Nowhere is this more significant than in littoral zones at the convergence of land–air–water (LAW) domains. In short, a comprehensive physics framework does not exist that can accurately predict how waveforms freely traverse these media boundaries resulting in a critical fundamental science knowledge gap that can correlate received waveforms to actual source generators. Furthermore, the preponderance of research has treated media boundaries as lossy reflectors rather than poor transmitters, resulting in a rudimentary understanding of wave transformation over subsurface inhomogeneities and boundaries. This article details the experimental component of a new transdisciplinary effort to characterize the full LAW wavefield within a littoral zone to overcome the mixed media challenges. The fusion of disciplines, including air and underwater acoustics, geophysics, and hydrology, aims to develop a full-wavefield description of coupled media in the environment. Beginning with a simplified scenario, the experimental design accommodates for measurements of wave transmission across land–water, air–water, and land–air boundaries in a controlled, constructed, and prototypical littoral zone. This article reviews the test site design, construction, and preliminary experimental results. The challenges of designing and implementing an experiment that explicitly observes signal propagation across the media boundaries without distorting the boundaries and includes sources and sensors in all three environments are discussed.

Negative group-delay assisted anomalous propagation in stacked Split Ring Resonator array

This paper explores a novel method to achieve negative group delay-assisted anomalous propagation without significant signal attenuation using stacked Split-Ring Resonator (SRR) array in the microwave regime. A sub-wavelength stacking thickness between the SRR layers creates transverse magnetic dipole moments due to the excitation of anti-parallel currents on these layers resulting in increased transmission amplitude. Multipole scattering theory has been utilized to extract the reason behind anomalous propagation by evaluating the scattered power from the principal electric and magnetic dipole moments excited on the structure. Time-domain analysis are performed on the samples, and negative group delay behavior is confirmed by observing the precedence of the output electromagnetic Gaussian pulse within the anomalous dispersion regime. The coupling effects are studied numerically using full-wave solvers and verified in experiments by performing transmission measurements inside an anechoic chamber.

Calibrated transmission and reflection from a multi-qubit microwave package.

We report calibrated microwave transmission and reflection measurements of a qubit sample holder at millikelvin temperatures. The methodology we present extends our previous work on one-port cryogenic short-open-load (SOL) calibration to a two-port SOLT measurement by implementing an unknown thru (T) standard. We report the resulting calibrated transmission and reflection at millikelvin temperatures through a printed circuit board that is installed into the sample holder. Finally, we consider a cascade of components at the end of a qubit drive line that includes (1) a cryogenic attenuator, (2) a coaxial cable, and (3) a qubit sample holder. Using experimentally determined parameters for return losses for all three components, we calculate the negligible state-preparation error in the frequency band of 5-7GHz due to control pulse distortions arising from reflection at the coaxial launches. Taken together, our results highlight the utility of calibrated cryogenic scattering parameter measurements for the validation of qubit packaging and the wiring in its immediate vicinity.

Udo Krüger Charts TechnoTeam's Journey

Udo Krüger Charts TechnoTeam's Journey