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We obtain several new sharp -continuity conditions, both necessary and sufficient, for operators of harmonic reflection of functions over boundaries of simple Carathéodory domains in . These results are based on a new criterion (also obtained in this paper) for -continuity of the Poisson operator in the aforesaid domains. As corollaries, we give new sufficient conditions for -approximability of functions by harmonic polynomials on boundaries of simple Carathéodory domains in . Bibliography: 17 titles.

We investigate the quantum transmission through the n-p-n heterojunction of massive 8-Pmmn borophene. It is found that the Dirac mass of the electron interacts nontrivially with the anisotropy of the 8-Pmmn borophene, leading to the occurrence of new transmission behaviors in this n-p-n heterojunction. Firstly, the effective energy range of nonzero transmission can be reduced but deviates from the mass amplitude, which induces the further controllability of the transmission property. Secondly, even if the equal-energy surfaces in the p and n parts do not encounter in the k-space, finite transmission is allowed to occur as well. In addition, the existence of Dirac mass can change the reflection manner from the retroreflection to the specular reflection under appropriate conditions. The findings in this work can be helpful in describing the quantum transport properties of the heterojunction based on 8-Pmmn borophene.

In this work, diamond-like carbon (DLC) films used as anti-reflective coatings for monocrystalline silicon were deposited by magnetron sputtering for potential application in solar cells. The microstructural and optical properties of the films were investigated as a function of substrate temperature over a wide range during deposition. It showed that, when the substrate temperature increased from RT to 800 °C, the hybridized structures of the DLC films accordingly changed associated with a significant variation of refractive index between2.22 and 1.64 at a wavelength of 550 nm. Three types of coating systems, namely single-, three- and five-layer films on monocrystalline silicon substrates, were designed based on the anti-reflection principle and fabricated in terms of the relationships of refractive index and deposition rate with substrate temperature. In particular, a well-designed three-layer film, of which the refractive index gradually changed along the thickness, that is 1.8, 1.9 and 2.0, respectively, was successfully deposited at one step on monocrystalline silicon substrates by adjusting substrate temperature and deposition time, and featured a broadband anti-reflective characteristic with low average reflectivity of 8.7% at a wide solar spectrum of 400–1100 nm. This work demonstrates that the DLC film has a promising application potential as broadband anti-reflective coatings in silicon-based solar cells.

Bound states can be supported on the surface of a periodically corrugated perfect conductor known as spoof surface plasmon polaritons with their dispersion curves reside below the light line. Here we show that bound states in the continuum (BICs) can also be achieved in such systems. Two types of grating structures are proposed to suppress the radiation leakage and hence generate bound states. The first one is a simple grating with broad grooves in which multiple cavity modes are accommodated. Due to the symmetry incompatibility and the destructive interaction mainly from the TM0 and TM1 modes, BICs at the Γ point and at off-Γ points are both realized. The second one is a dimerized grating with two grooves in each unit cell. The destructive interaction between the modes in the two grooves can suppresses the radiation and BICs at the Γ point are observed. The Q factors of the whole bands can be further tuned by the dimerization strength effectively. This work may offer new opportunity for the applications of metallic grating in the low frequency bands.

This research is motivated by the researcher’s desire to see the folding and rotational symmetry in geometric shapes whether they meet the symmetries for certain aspects and form a group. The method used in testing the symmetry of a group in geometric shapes is by testing reflection and rotation with a combination of linear and abstract algebra using an ordered matrix, where the geometric shapes are traced on each particular aspect until they meet the symmetry. From the results of the method used, it is found that the triangles to the octagon groups are symmetrical through the test of rotation and reflection of the geometric shapes. Thus, it can be concluded that group symmetry occurs up to the order of eight in geometric shapes. Based on the pattern, starting from the pentagon it is not a symmetry group, the hexagon includes the symmetry group, the heptagon is not a symmetry group, the octagon includes a symmetry group, then the nonagon is not a symmetry group and the decagon belongs to the symmetry group

A broadband stigmatic (imaging) soft X-ray (λ > 120 A) spectrometer is experimentally realised. The optical configuration of the spectrometer comprises a plane grazing-incidence reflection grating with a spacing varying across its aperture according to a preassigned law [a so-called varied line-space (VLS) grating] and a broadband spherical normal-incidence mirror with an aperiodic Mo/Si multilayer structure. The average plate scale amounts to ~5.5 A mm−1. The radiation is recorded with a matrix CCD detector (2048 × 1024 pixels of size 13 μm). The line spectra of the multiply charged ions LiIII and FV–FVII excited in laser-produced plasma are recorded with a spatial resolution of ~26 μm and a spectral resolving power R ≈ 500 is experimentally demonstrated.

We investigated the resonance splitting in microring resonators (MRRs) constructed from nanofibers of organic dye, which function as active waveguides. The MRRs were fabricated by connecting both end parts of a nanofiber so that they contacted with each other in a side-by-side manner with a contact length of ∼5 μm by micromanipulation on a substrate. We observed that the shape and width of the resonance peaks were sensitively changed by changing the contact length. Moreover, the resonance peaks split into a doublet by tuning the contact length. We propose that the splitting is due to the coupling between the counterclockwise and clockwise traveling modes within a ring. The coupling can be induced by the reflection of traveling light at the end faces of the nanofiber in the connection region. Since this mechanism leads to a strong mode coupling, the resonance splitting is resolved even though the resonance peaks of the nanofiber MRRs are relatively broad (the Q-factors of up to ∼2000).

The probability of reflection R(E) off a finite attractive scattering potential at zero or low energies is ordinarily supposed to be 1. However, in Ahmed Z et al (2017 Eur. J. Phys. 38 025401) we proposed that a fully attractive potential presents a paradoxical result of R(0) = 0, when an effective parameter q of the potential admits special discrete values. In an interesting comment to Ahmed et al (2017 Eur. J. Phys. 38 025401); by 5van Dijk and Nogami (2017 Eur. J. Phys. 38 038002), another class of finite potentials turned out to be of the well–barrier type, which can be made to possess much less reflection at zero and low energies for a band of low values of q. Such well–barrier potentials have only two real turning points for E ∈ (min (V(x)), max (V(x))), excepting E = 0. Here, we wish to add one more exactly solvable and two numerically solved models to confirm this phenomenon in the well–barrier systems.

Space-charge limited current flow between DC biased electrodes is a widely applicable problem in many areas of physics. Recently, radio-frequency biasing, together with DC self-bias formation, has been studied as a new concept for the extraction of charged particles from an upstream plasma source. Here, we compare particle extraction between systems using this hybrid AC/DC biasing, with conventional DC biased electrodes, and identify important similarity parameters. The injection current first leading to particle reflection strongly depends on the applied AC frequency and voltage magnitude, as well as the initial particle injection velocity, and is in general lower than the DC case. For injection currents above the AC limit, the system becomes unstable, and self-excited space-charge oscillations are generated. A critical parameter is the ratio of the average particle transit time between the electrodes to the AC period, γ = t L/T. As long as γ ≫ 1, the onset of particle reflection can be sufficiently delayed that the extracted current approaches the DC limit.

AlN single crystal grown by physical vapor transport (PVT) using homogeneous seed is considered as the most promising approach to obtain high-quality AlN boule. In this work, the morphology of AlN single crystals grown under different modes (3D islands and single spiral center) were investigated. It is proved that, within an optimized thermal distribution chamber system, the surface temperature of AlN seed plays an important role in crystal growth, revealing a direct relationship between growth mode and growth condition. Notably, a high-quality AlN crystal, with (002) and (102) reflection peaks of 65 and 36 arcsec at full width at half maximum (FWHM), was obtained grown under a single spiral center mode. And on which, a high-quality Al x Ga1– x N epitaxial layer with high Al content (x = 0.54) was also obtained. The FWHMs of (002) and (102) reflection of Al x Ga1– x N were 202 and 496 arcsec, respectively, which shows superiority over their counterpart grown on SiC or a sapphire substrate.

In this paper, a deep learning method based on polarization image is proposed. Firstly, the polarization characteristics of reflected light and transmitted light are analyzed by using the Fresnel’s law. Then, based on the polarization characteristics that the reflected light is polarized in the perpendicular direction and the transmitted light is polarized in the parallel direction, the polarization images obtained from the parallel direction and the perpendicular direction are input into the Encoder-Decoder net at the same time, and the net is trained by L1 loss. The experimental results show that by combining the polarization information and deep learning method, the reflected component and transmitted component can be effectively separated.

Transmission of electrons across a rectangular barrier of IV-VI semiconductor compounds is considered. Conduction electrons arrive at the barrier and are reflected or transmitted through it depending on the relative values of the barrier potential $V_b$ and the electron energy $E$. The theory, in close analogy to the Dirac four component spinors, accounts for the boundary conditions on both sides of the barrier. The calculated transmission coefficient $T_C$ is an oscillatory function of the barrier voltage varying between zero (for full electron reflection) and unity (for full electron transmission). Character of electron wave functions outside and inside the barrier is studied. There exists a total current conservation, i. e. the sum of transmitted and reflected currents is equal to the incoming current. The transmission $T_C$ is studied for various barrier widths and incoming electron energies. Finally, the transmission coefficient $T_C$ is studied as a function of $V_b$ for decreasing energy gaps $E_g$ of different Pb$_{1-x}$Sn$_x$Se compounds in the range of 150 meV $\geq E_g \geq$ 2 meV. It is indicated that for very small gap values the behaviour of $T_C$ closely resembles that of the chiral electron tunneling by a barrier in monolayer graphene. For $E_g$ =0 (Pb$_{0.81}$Sn$_{0.19}$Se) the coefficient $T_C$ reaches the value of 1 independently of $V_b$., Comment: 6 pages, 5 figures

We studied the structural, electronic, and optical characters of SiS2, a new type of group IV–VI two-dimensional semiconductor, in this article. We focused on monolayer SiS2 and its characteristic changes when different strains are applied on it. Results reveal that the monolayer SiS2 is dynamically stable when no strain is applied. In terms of electronic properties, it remains a semiconductor under applied strain within the range from −10% to 10%. Besides, its indirect band-gap is altered regularly after applying a strain, whereas different strains lead to various changing trends. As for its optical properties, it exhibits remarkable transparency for infrared and most visible light. Its main absorption and reflection regions lie in the blue and ultraviolet areas. The applied uniaxial strain causes its different optical properties along the armchair direction and zigzag direction. Moreover, the tensile strain could tune its optical properties more effectively than the compressive strain. When different strains are applied, the major changes are in blue and ultraviolet regions, but only minor changes can be found in infrared and visible regions. So its optical properties reveal good stability in infrared and visible regions. Therefore, SiS2 has a promising prospect in nano-electronic and nano-photoelectric devices.

We consider the problem of a semiclassical description of quantum chaotic transport, when a tunnel barrier is present in one of the leads. Using a semiclassical approach formulated in terms of a matrix model, we obtain transport moments as power series in the reflection probability of the barrier, whose coefficients are rational functions of the number of open channels M. Our results are therefore valid in the quantum regime and not only when $M\gg 1$. The expressions we arrive at are not identical with the corresponding predictions from random matrix theory, but are in fact much simpler. Both theories agree as far as we can test., 17 pages, 5 figures

We report a hybrid cavity structure based on a suspended microfiber with a diameter of 1.7 μm applied to nanoparticle sensing in water. The proposed hybrid cavity is composed of two symmetrical reflectors with a slotted Au layer in the middle. After being characterized by the finite-difference time-domain method, the obtained strong reflection and sufficiently wide band gap provide the potential to realize an ultrasmall mode volume, which can improve sensitivity and lower loss. In addition, an ultrahigh Q/V ratio of 8.2 × 106 (λ/n)−3 and high resonance transmittance of T = 0.53 can be obtained through optimization analysis. After analyzing the trapping force and resonance shift caused by the change in local electric field, it is proven that our proposed cavity exhibits a high sensitivity and offers a convenient and stable method for particle sensing in water.

We present a study on the evolution of both transverse and longitudinal energy distributions due to oxygen–induced quantum efficiency degradation in the electrons emitted from a reflection–mode p-GaAs(Cs,O)-photocathode over an effective electron affinity range of χ *∼ −0.1 eV to χ *∼ +0.3 eV under illumination wavelengths λ = 808, 635 and 532 nm. For λ = 635 and 532 nm, we found that the mean transverse energy of electrons emitted as the photocathode effective electron affinity increased has a non–monotonic character. Our proposed fitting model links the measured response to changes in the relative number of thermalised and non–thermalised electrons in the total emitted photocurrent.

The present study aimed to evaluate the optical properties of 1D photonic crystal (PC) with a defect layer doped by four-level InGaN/GaN quantum dots. Transient and steady-state behavior of the medium completely relies on the intensities and relative phases of coherent coupling fields. In addition, the transient absorption–dispersion spectra of 1DPC can be easily adjusted by choosing the controllable parameters properly. Furthermore, the transmitted and reflected light pulses at λ = 1.55 μ m (long wavelength) can be tuned by controlling the Rabi frequencies of applied light due to their potential applications in all-optical systems. Furthermore, the effect of relative phase between applied fields on the light propagation was evaluated through the medium. In addition, all-optical switching time was found for subluminal/superluminal and absorption/transmission of light propagation. The required switching time ranges between 2–7 ps. The proposed model may provide some new possibilities for technological applications in optoelectronics and solid-state quantum information science and systems due to large applications in signal processing.

The recent significant growth of telecommunications systems, especially in radar applications, has created a sustained need for more smart materials for detecting and/or concealing given objects from radar systems. Key contributing factors in this respect are the reflection and transmission coefficients of such composite materials. The two main methods for calculating the reflection and transmission coefficients are non-resonant and resonant methods. In this work, non-resonant reflection/transmission methods are used to calculate the reflection and transmission coefficients of polymer composites mixed from 1 - 4 wt% of Nano-PZT (Lead Zirconium Titanate). The calculation of the reflection and transmission coefficients is carried out experimentally using an electromagnetic wave on a single layer made from this material. Results show that the transmission coefficient reached a maximum value at 10 GHz, while the reflection coefficient reached a maximum value at 8-9 GHz for all the distance 50-160mm.

The reflection high-energy electron diffraction (RHEED) method is widely used for the in situ observation of molecular beam epitaxy (MBE). This is because the RHEED pattern dynamically changes according to the growth conditions, such as surface temperature and material supply. However, to date, the RHEED pattern has been categorized and recognized based on the experience of the researcher. In this study, we investigated the classification of RHEED pattern datasets without using labeling by the principal component analysis method that reduces the dimensionality of the data. The RHEED images were successfully classified during the MBE growth of GaAs, demonstrating that unsupervised learning can be used to recognize RHEED patterns.

A general homogenization procedure for periodic electromagnetic structures, when applied to layered media with asymmetric lattice cells, yields an effective tensor with magnetoelectric coupling. Accurate results for transmission and reflection are obtained even in cases where classical effective medium theory breaks down. Magnetoelectric coupling accounts for symmetry breaking in reflection and transmission when a non-symmetric structure is illuminated from two opposite sides.

The measurement of black hole spin is of great significance. The methods of measuring the spin have been discussed for a long time. For this important astrophysical problem, the paper begins with the significance of measuring a black hole spin and focuses on the theory of measuring the spin via the X-ray reflection recognized as iron line spectrum method. The paper also discusses the popular reflection models and explains the important parameters. Besides, the other methods of spin measurement are introduced, mainly comparing them with the X-ray reflection method. Finally, the advantages and disadvantages of the X-ray reflection method are summarized.

Quantum dots (QDs) are fundamental elements in the applications related to light–matter interaction, such as solar cells, lasers and sensors. Moreover, some modes of electrons including whispering galley modes (WGMs) and surface modes can be incorporated in many electronic systems, in high Q-resonators, and quantized reflection/transmission. Therefore, controlling and manipulating their energy spectra is vital. Here, we investigate energy spectra as well as WGM and surface mode of electrons in lateral and corrugated QDs. Although, lateral QDs are usually modelled by a 2D harmonic oscillator (with zero thickness), we show that even very small thickness of dots can change their energy spectra, also they can contain surface mode of electrons. Moreover, we investigate WGM in deformed QDs, and the dots which contain corners in their outermost region, and show that some degenerated points would be created. Meanwhile, in the corrugated QDs, the wavefunction would be distributed in the specific teeth based on its energy level.

Molybdenum disulfide (MoS2) on the c-plane sapphire has been a very popular system to study in the two-dimensional (2D) materials community. Bottom-up synthesis of monolayer (ML) MoS2 with excellent electrical properties has been achieved on sapphire by various methods, making it a very promising candidate to be used in the next generation nano-electronic devices. However, large-area ML MoS2 with comparable quality as the relatively small size exfoliated ML remains quite a challenge. To overcome this bottle neck, a comprehensive understanding of the structure of the as-grown ML material is an essential first step. Here, we report a detailed structural characterization of wafer-scale continuous epitaxial ML MoS2 grown by metalorganic chemical vapor deposition on sapphire using an azimuthal reflection high-energy electron diffraction (ARHEED) technique. With ARHEED we can map not only 2D but also 3D reciprocal space structure of the ML statistically. From the oscillation in the ARHEED intensity profile along the vertical direction of the ML, we derived a real space distance of ~3 Å at the interface of ML and sapphire. Quantitative diffraction spot broadening analyses of the 3D reciprocal space map reveals low density defects and a small angular misalignment of orientation domains in ML MoS2. Based on atomic force microscopy height distribution analysis, cross-section scanning transmission electron microscopy, and density functional theory calculations, we suggest that there exists a passivation layer between MoS2 ML and sapphire substrate. This ARHEED methodology also has been applied to ML WS2 and is expected to be applicable to other ML transition metal dichalcogenides on arbitrary crystalline or non-crystalline substrates.

The research object is multilayer photosensitive structures with a porous silicon working layer and a semiconductor zinc sulphide. The purpose of this work is to study the effect of the zinc sulphide coating thickness on the structure optical properties. The reflection and photosensitivity spectral characteristics of structures with various thicknesses zinc sulphide coating were studied. It was shown that the optimal coating thickness is 0.056 micrometers.

In this work, we have studied the phase switching in structures based on the Ge2Sb2Te5 (GST) composition and their optical parameters of reflectivity and transmissivity at 1550 nm wavelength after exposure to the pulse of nanosecond laser at 403 nm wavelength. We investigated 24 nm GST single-layer structure and found about 50% optical losses due to the double reflection and transmission at 1550 nm radiation. To achieve the least optical losses, we added additional SiO2, Si and Si3N4 layers to the structure. This allowed reducing optical losses up to 5 and 4% for absorption and undesirable reflection, respectively, for the amorphous GST layer, and 16 and 5% for absorption and undesirable transmittance, respectively, for the crystalline GST layer.

The aim of the work is to investigate different approaches for the growth of planar gallium phosphide layers on silicon by molecular beam epitaxy. Atomic force microscopy and reflection high energy electron diffraction were used to study surface morphology and estimate the film domain structure. Developed growth technique with the use of a low-temperature AlGaP/GaP seeding layer allowed us to achieve atomically flat pseudomorphic single-phase GaP on Si(001).

The influence on the optical properties of AR Low-E PVD coatings with silver IR-reflectors on glass substrates from the water absorption into their outer ZnSnOx dielectric layers was considered with the use of VIS/NIR-spectrophotometry. The estimations of coatings absorption shift reversibility depending on the initial contact with water duration as well as of the mechanisms responsible for the changes in optical constants of the stack’s layers, supported with the comparative analysis of experimental and modelled spectra, are reported. It was shown that the water vapour sorption within the top zinc stannate layer leads to the shift in optical qualities of the whole stack by the changes in the stack’s absorption spectrum in the visible range. This effect proved to be reversible with the water exclusion via the samples heat treatment, but only until the water diffusion into the depth of the Low-E stack reaches the Ag layers, propagating the aggregation, that can no longer be cured with the temperature impact. The change in integral visible-range absorption reaches up to ?Avis = 0.5-1 abs.% in comparison to the “as-deposited” samples, suggesting that the presented observations can be employed for VIS/NIR-spectrophotometry of such coatings for the purpose of their initial wetting determination, as well as the control of their further degradation.

In this work results of a nanocomposite structures optical parameters modelling are presented. The variable parameters were: shape of nanoinclusions, matrix width and incident radiation angle. The quasiperiodic nanocomposite structures consisting of a titanium dioxide matrix and gold nanoparticles were simulated. A spectral analysis of these structures showed the nonlinear nature of the absorption and reflection spectra and influence of the nanoparticles shape on it.

We investigate the comparison method and the substitution method of integrating sphere-based relative methods for reflection measurements. Through an analytical description, we compare the two methods with a focus on the effects of a sphere: to determine reflectance without any correction on a sphere, the substitution method requires symmetry of a sphere in addition to the requirement of the comparison method, either uniformity of a sphere or equal reflectance distribution between a sample and a reference. We experimentally compare the two methods through reflection measurements of gray-scale diffuse samples with reflectance of 10%, 40%, and 99%, which results in agreement within their measurement uncertainties. Also, we observe a reflectance change depending on sample location on a sphere in the substitution type measurements, which is attributed to sphere's lack of symmetry. The experimental results are analyzed in terms of measurement uncertainty and reflection properties including bidirectional reflectance distribution function.

We investigate theoretically single photon transport properties in coupled-resonator waveguide coupling with a nanocavity interacting with an external mirror. By using the discrete coordinates approach, transmission and reflection amplitudes of the propagating single photon in the waveguide are obtained. The influence of the coupling strength between the nanocavity and the external mirror on the single photon scattering spectra is discussed. We also extend the results to the waveguide with linear and quadratic form dispersion relations.

Medical ultrasound imaging scanners typically display the envelope of the reflected signal on a log scale. The properties of this image and speckle patterns from collections of scatterers have a number of well-known disadvantages. One is the inability to differentiate between different scatterers that may have fundamentally different frequency-dependent scattering cross sections. This study proposes a framework for characterizing scattering behavior and visualizing the results as color coding of the B-scan image. The methodology matches a model of pulse-echo formation from typical situations to the mathematics of Gaussian weighted Hermite functions. The results show an ability to reveal some of the information otherwise hidden in the conventional envelope display, and can be generalized to more conventional bandlimited pulse functions. This new class of images is termed H-scan where 'H' stands for 'Hermite' or 'hue' to distinguish it from conventional B-scan format.

Numerical modelling demonstrates the possibility of fabricating an all-fibre multibeam two-mirror reflection interferometer based on a metal–dielectric diffraction structure in its front mirror. The calculations were performed using eigenmodes of a double-clad single-mode fibre. The calculation results indicate that, using a metallic layer in the structure of the front mirror of such an interferometer and a diffraction effect, one can reduce the Ohmic loss by a factor of several tens in comparison with a continuous thin metallic film.

Intelligent Reflection Surface (IRS) and low-resolution analog-to-digital converters (ADCs) are proven to be efficient ways to release the burden of power consumption for future wireless systems. In this paper, the effect of IRS and quantization on the performance of multiple-input multiple-output (MDVIO) channels is investigated in terms of channel capacity. The reflection matrix of the IRS and analog combiner matrix are optimized jointly. To this end, the expression of capacity with low SNR is derived, and the optimization problem of the reflection matrix is converted to semidefinite programming (SDP). A gradient-based approach is proposed to optimize the analog combiner matrix and the reflection matrix in a general case. Simulation results are provided to assess the performance of proposed designs, it is shown that the IRS can improve the performance of the system where there is no line-of-sight channel to some extent, and a larger capacity could be obtained in low SNR expression than general expression under same conditions.

The manipulating of optical waves in a microcavity is essential to developing the integrated optical devices. Generally, the two eigenmodes in a whispering-gallery-mode (WGM) microcavity possess chiral symmetry. Here we show the chiral symmetry breaking is induced by the asymmetric backscattering of counter-propagating optical waves in a whispering-gallery-mode (WGM) microcavity with a cavity-made slot filled with atomic vapor. Through tuning the dispersion relation of the atomic vapor in the cavity-made slot, the chiral modes are continuously steered. The mode frequency splitting in the transmission and reflection spectra stem from the chiral symmetry breaking of the two eigenmodes. The displacement sensitivity of the proposed system in response to the length variation of cavity-made slot exhibits a high sensitivity value of 15.22 THz/nm.

A highly transparent and super-hydrophilic double-layer anti-reflection coating was prepared by a simple and economical sol-gel method based on the glass substrate. The bottom and top layer were respectively made with SiO2–TiO2 sol and SiO2–TiO2-PEG300 sol. The average transmittance of the substrate coated with the double-layer coating is increased by 7% up to 97.4% in the visible light band, and the peak transmittance reaches 99% at about 550 nm. In addition, double-layer anti-reflection coating shows a good super-hydrophilic self-cleaning performance, and the transmittance of the coating can be restored by simple washing with water. Furthermore, due to the existence of anatase TiO2, the composite coating can restore the super-hydrophilicity damaged by dust under UV light.

A back-projection (BP) algorithm based on cross-correlation (CBP), which is both fast and good at suppressing artifacts, is adopted here for through wall imaging (TWI). Firstly, by “moving” the wall to the image point, the three layer TWI modal is equivalent to the two layer TWI modal. By doing so, only half of the reflection points are needed to be calculated; secondly, to further reduce the calculation time, on the one hand, the symmetric-invariant property as well as the shift-invariant property of the ray propagation is used to calculate the look-up table, on the other hand, the delay-multiply-sum equation in CBP is rewrite into a new form with less addition and multiply computation. Simulation results show the superiority of the proposed CBP algorithm both in operation speed and artifacts suppression.

Humans often encounter obstacles in doing their work. Especially if the work is related to an emergency situation that concerns the safety of human life, it needs quick and appropriate handling. Telerobotic technology that has a haptic function is one solution to these problems. In this study a system of 1 DOF haptic manipulator with slave master configuration was developed using bilateral haptic manipulator control. In bilateral control the position and information are transmitted in two directions between two manipulators. Position information is obtained using a potentiometer and force information is obtained by representing the force with the current using the WCS2702 sensor. There are three control methods used, namely bilateral symmetrical position control, bilateral reflection force control and force feedback bilateral control. The best method of control is the bilateral feedback force control. In the force feedback bilateral control system, the slave can move following the master movement with a ± 2° position error. When the slave arm is held by a hard object, the master arm is also restrained with ± 11° position error. Whereas when the slave arm is held by a soft object, the reflection of the object is felt by the master arm with ± 10 position error. Movement of the master and slave arms is lighter than using bilateral control of symmetrical position.

The Numerical Advanced Model of Electron Cyclotron Resonance Ion Source (NAM-ECRIS) is applied for studies of the physical processes in the source. Solutions of separately operating electron and ion modules of NAM-ECRIS are matched in iterative way such as to obtain the spatial distributions of the plasma density and of the plasma potential. Results reveal the complicated profiles with the maximized plasma density close to the ECR surface and on the source axis. The ion-trapping potential dips are calculated to be on the level of ~(0.01-0.05) V being located at the plasma density maxima. The highly charged ions are also localized close to the ECR surface. The biased electrode effect is due to an "electron string" along the source axis formed by reflection of electrons from the biased electrode and the extraction aperture. The string makes profiles of the highly charged ions more peaked on the source axis, thus increasing the extracted ion currents.

We study the single-photon transport in the coupled-resonator waveguide (CRW) controlled by an imperfect cavity. A Lorentzian spectrum is introduced to describe the dissipation. We find that the probability current conservation can be broken, although the imperfect cavity is a Hermitian system. The coupling strength between the imperfect cavity and the CRW has significant influences near the resonant frequency. With the increase of the coupling strength, the transmission coefficient becomes smaller. The spectral width plays a dominant role under the off-resonant condition, where the transmission coefficient is greatly suppressed with the increase of the spectral width. We also observe an abrupt jump of the transmission and reflection coefficients when the hopping amplitude is large enough. All the distinctive behaviors are closely related to the complex effective potential induced by the imperfect cavity., 7 pages, 6 figures

ZnS/Au/ZnS (ZAZ) transparent conductive tri-layer films with different Au layer thickness have been prepared by a pulsed laser deposition technique, and the effect of Au layer thickness on the optical and electrical properties of ZAZ films has been studied in detail. As-deposited ZAZ films showed an intense X-ray diffraction peak corresponding to ZnS (111) orientation and a very weak peak belonging to the Au (111) plane. The optical transmittance first increases and then decreases with the increase of Au layer thickness, which is due to the fact that Au changes from discontinuous island-shape to near-continuous structure when Au increases from 2 to 10 nm, and when Au is above 10 nm, the reflection of Au layer is enhanced. With the increase of Au layer thickness, both the sheet resistance and the resistivity of ZAZ films decrease, and the carrier concentration and the mobility increase. When the Au layer thickness is 10 nm, ZAZ films have the best figure of merit of 2.44 × 10−3 Ω−1.

We consider a quantum particle with energy E incident upon a one-dimensional potential. We show that the probabilities of transmission and reflection are the same for incidence upon a general potential from either side (from 'the left' or 'the right'). This equality holds true for any potential which goes to constant values as and is finite for all x. We present a remarkably simple proof that the probabilities are equal. The simplicity of our proof is the most important pedagogical result of our paper, and will be easily understood by undergraduate students in second to fourth year. We discuss several cases, including the step potential and the potential barrier.

Plasmonic nanostructure-based refractive index (RI) sensors are the core component of biosensor systems and play an increasingly important role in the diagnosis of human disease. However, the costs of traditional plasmonic RI sensors are not acceptable to everyone due to their expensive fabrication process. Here, a novel low-cost and high-performance visible-light RI sensor with a particle-on-film configuration was experimentally demonstrated. The sensor was fabricated by transferring annealed Au nanoparticles (NPs) onto a thin gold film with polymethyl methacrylate (PMMA) as a support. RI sensitivities of approximately 209 nm/RIU and 369 nm/RIU were achieved by reflection and transmission spectrum measurements, respectively. The high sensitivity is due to the strong plasmon-mediated energy confinement within the interface between the particles and the film. The possibility of wafer-scale production and high working stability achieved by the transfer process, together with the high sensitivity to the environmental RI, provides an extensive impact on the realization of universal biosensors for biological applications.

This paper presents a new rear-triggered vanadium-compensated 4H silicon carbide (4H-SiC) photoconductive semiconductor switch (PCSS) with aluminum nitride (AlN) anti-reflection coating on the back of PCSS device. Characteristics of PCSS are investigated by using semiconductor device simulation software Silvaco-TCAD. The switch substrates were doped with vanadium to make the substrates highly insulated. The on-state performance of the photoconductive switch was tested under pulsed light conditions with a wavelength of 532 nm and an optical power density of 6.8 MW/cm2 at a bias voltage of 2 kV. And the bias voltage was increased from 0 V to 10 kV in the absence of light trigger conditions, and its off-state characteristics were tested. Results show that the electric field strength between electrodes can be reduced by using rear-triggered structure, the switch breakdown voltage is over 80 kV DC, the maximum transient current is about 137 A, and the tail current almost disappears when the pulse light is turned off. In addition, the breakdown voltage of the rear-triggered PCSS to be higher than that of the front-triggered one. After adding AlN anti-reflection coating on the switch, the maximum transient of the switch and the optical utilization efficiency of laser energy are significantly improved, the maximum transient current of the switch was greatly improved from137 A to 150 A, which was increased by about 9.4 %. In addition, the effects of substrate thickness and optical power density on the switching performance were evaluated.

We consider the scattering problems of a quantum particle in a system with a single Y-junction and in ring systems with double Y-junctions. We provide new formalism for such quantum mechanical problems. Based on a path integral approach, we find compact formulas for probability amplitudes in the ring systems. We also discuss quantum reflection and transmission in the ring systems under scale-invariant junction conditions. It is remarkable that perfect reflection can occur in an anti-symmetric ring system, in contrast with the one-dimensional quantum systems having singular nodes of degree 2., Comment: 9 pages, 3 figures

We study transport through a single-level system placed between two reservoirs with band-structure, taking strong level-reservoir coupling of the order of the energy-scales of these band-structures. An exact solution in the absence of interactions gives the nonlinear Lamb shift. As expected, this moves the perfectly-transmitting state (the reservoir state that flows through the single-level without reflection), and can even turn it into a bound-state. However, here we show that it can also create additional pairs of perfectly-transmitting states at other energies, when the coupling exceeds critical values. Then the single-level's transmission function resembles that of a multi-level system. Even when the discrete level is outside the reservoirs' bands, additional perfectly-transmitting states can appear inside the band when the coupling exceeds a critical value. We propose observing the bosonic version of this in microwave cavities, and the fermionic version in the conductance of a quantum dot coupled to 1D or 2D reservoirs., Comment: Published version plus extra appendices (9 pages with 6 figures)

In order to improve the effect of image acquisition under the condition of low illumination, a low illumination image enhancement algorithm based on multi-feature fusion is adopted in this paper. In this algorithm, the illumination information is extracted by bilateral filtering, and the illumination parameters are processed by adaptive gamma correction and limited contrast histogram equalization algorithm. The final illumination parameters are obtained by the feature weighted fusion of the processed parameters and the original illumination parameters. The RGB image is obtained by combining the illumination and reflection parameters, and the enhancement of the image is realized. The experimental results show that the algorithm used in this paper can not only improve the brightness of the image, but also enhance the characteristic parameters of the image, remove the noise, and make the color information of the image fuller and richer

Based on the Bogoliubov-de Gennes equation, the quantum scattering problem through a nodal-line Weyl semimetal based normal metal/superconductor heterojunction has been theoretically studied. Since the crystallographic anisotropy in the material, two different orientations between the crystalline axis and the superconducting interface have been revealed. Considering a heterojunction with the interface paralleling to the basal plane, it is found that Andreev reflection with [Formula: see text] due to Klein-like scattering gives rise to a perfect scattering. Deviation from the critical value, Andreev reflection falls down and normal reflection goes up. While the interface is perpendicular to the basal plane, the pure intra-mode retro-Andreev reflection (RAR) and inter-mode specular Andreev reflection (SAR) are manifested at the normal incident. Moreover, the reflection coefficient exhibits the reentrant behavior with the Fermi energy. Fundamentally, such features are a consequence of the torus-like iso-energy surfaces of the nodal-line Weyl semimetals, which is in sharp contrast to the case of conventional materials, graphene, and Weyl-point semimetals. Those novel scattering processes also result in a distinctive tunneling conductance, such as the sub-gap nonmonotonic features, the interface directional dependent zero bias conductances and the reentrant behavior, which can be served as a smoking gun to distinguish the mode-resolved Andreev reflections in experiments.

In this work, a theory for the scattering of two-dimensional plane-waves from a periodic, one-dimensional array of nonmagnetic, localized scatterers in the presence of Rashba spin-orbit coupling is presented. Formulas for the spin-subband resolved transmission and reflection coefficients along with the transmitted and reflected wave functions are derived. In the presence of spin-orbit coupling, the Talbot effect, where periodic modulations in the transmitted probability density arise along a direction orthogonal to the periodic direction of the scattering potential, is shown to occur. However, it is demonstrated that Rashba spin-orbit coupling increases the complexity of the observed interference patterns where different types of Talbot lengths due to both alt;iagt;interspinalt;/iagt; and alt;iagt;intraspinalt;/iagt; subband scattering are predicted. Numerical calculations are provided to support the theoretical calculations presented in this work.