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The vibrational and electronic properties of the Pb-doped dichalcogenide PbxTaSe2 (x = 0, 0.25, 0.33, 0.5, 0.75, and 1) have been investigated using Raman scattering experiments. A marked variation of the main vibrational modes with Pb concentration x is observed. The concentration dependence of the vibrational modes resembles the dependence of the vibrational modes in TaSe2 on the number of crystallographic layers along the c-axis direction. The temperature and polarization dependences of Raman spectra of PbxTaSe2 revealed additional broad modes in the low-frequency regime, which are discussed in the context of the remnant charge density wave, induced disorder, or PbSe phase formed in the interface of Pb and TaSe2 layers.

The first-harmonic approximation of the Ginzburg–Landay theory was used to analyze the influence of magnetic field H along the y axis (modulation direction of manganese spins) in incommensurate AFM phases in the orthorhombic TbMnO3 film. It was shown that an increase in magnetic field and a decrease in the film thickness lead to the decrease in the Neel temperature. The dependence of the Neel temperature on magnetic field in the TbMnO3 film was obtained. The boundary lines between modulated AFM phases in magnetic field are changed weakly besides some increase in the temperature Tc = 28 K at H = 0. It means the conservation of the colossal magnetoelectric effect of the “polarization flop in magnetic field” in the manganite terbium films up to 6 nm thickness. Therefore, such TbMnO3 films (3 periods of the spin cycloid) can become a basis of future nanotechnology of the magnetoelectric devices.

We suggest a novel approach to predict and clarify the transformation of an arbitrarily polarized wave into two circularly polarized ones, based on the peculiar features of their transmission and reflection from a stack with regularly arranged gyrotropic layers. In spite of the fact that in the Faraday geometry gyrotropic media possess four electromagnetic eigenmodes, we have managed to modify the problem to be analytically resolved within the conventional transfer-matrix method. As a result, we have obtained and analyzed the dispersion relation, as well as the transmission and reflection coefficients, which are applicable for any elliptic polarization of a wave irradiating a gyrotropic superlattice with finite number of unit cells. It is shown that there exists a wide range of wave frequency and magneto-optical parameter (proportional to external dc magnetic field) inside of which the wave of given circular polarization is perfectly transmitted, while the wave with the opposite circular polarization is completely reflected. Thus, under certain conditions, the incident plane wave (taken as an appropriate example) splits up into the transmitted and reflected circular waves with mutually inverse rotations. We indicate conditions when a relatively small variation of the magnetization can reverse the polarizations mentioned above.

The results of experimental investigations on the low-temperature fluorescence and absorption spectra of the 1- and 2-fluoronaphthalene impurities in the crystalline naphthalene are presented and analyzed. When the 1- and 2-fluoronaphthalene concentrations are less than 1%, the absorption and fluorescence spectra are shown to be composed of two identical band series, induced by the formation of two different centers, consisting of the single impurity molecules. The impurity concentration increase of over 1% results in the appearance of the additional structure in the polarized absorption spectra near the 0-0 bands of the single centers in a form of narrow bands with similar intensity and different polarization. This structure is associated with a formation of impurity paired centers, consisting of the two resonantly interacting molecules of either 1-fluoronaphthalene, or 2-fluoronaphthalene. Besides, in the case of the 2-fluoronaphthalene, the absorption spectra contain intense peaks, located ∼ 45 cm−1 higher in frequency, relative to the 0−0 transition bands for each single-center, and consisted of complexes of narrow lines. These spectral peaks are also explained by a formation of impurity paired centers, but here interactions between the molecules are not resonant. For the pure naphthalene crystal factors, causing the observation of additional oppositely polarized weak bands in the absorption spectra at ∼ 10 cm−1 near the Davydov doublet components, are described.

We report on an electron-spin resonance study of nuclear polarization of hydrogen atoms embedded in solid H2 and HD films at temperatures 0.1–1.5 K and in a high magnetic field of 4.6 T. Similar to our previous work [Phys. Rev. Lett. 122, 225301 (2019)], we observed a build-up of the spontaneously ( p ≃ 0.35 ) and highly ( p ≃ 0.75 ) nuclear polarized phases of H atoms in the as-deposited H2 films. However, we did not obtain an enhanced nuclear polarization of H atoms in the regions of their small local concentration. We also failed to observe enhanced nuclear polarization for H atoms in the annealed H2 films as well as in the as-deposited HD sample. These observations tend to support our previous explanation for the build-up of high nuclear polarization due to the formation of weakly-bound triplet H2 molecules.We report on an electron-spin resonance study of nuclear polarization of hydrogen atoms embedded in solid H2 and HD films at temperatures 0.1–1.5 K and in a high magnetic field of 4.6 T. Similar to our previous work [Phys. Rev. Lett. 122, 225301 (2019)], we observed a build-up of the spontaneously ( p ≃ 0.35 ) and highly ( p ≃ 0.75 ) nuclear polarized phases of H atoms in the as-deposited H2 films. However, we did not obtain an enhanced nuclear polarization of H atoms in the regions of their small local concentration. We also failed to observe enhanced nuclear polarization for H atoms in the annealed H2 films as well as in the as-deposited HD sample. These observations tend to support our previous explanation for the build-up of high nuclear polarization due to the formation of weakly-bound triplet H2 molecules.

The observation of the thermoelectric effect, which is the spontaneous electric polarization of a cell with liquid He II during the thermal excitation of standing second-sound waves, has been confirmed [Low Temperature Physics 30, 1321 (2004)]. The relationship of this effect with the thermal and hydrodynamic properties of He II is studied in detail in the temperature range of 1.4 K w0, the electric response becomes random in nature as the fluctuations increase and the amplitude decreases to zero, with a peculiar electromagnetic “noise” being observed. The experimental results are compared with the conclusions drawn from the theory of flexoelectric polarization of liquid helium. The polarization of liquid helium upon excitation of the first-sound waves, as well as pressure and temperature shock waves, has also been discussed.

Enhancement of fluorescent radiation is of great importance for applications including biological imaging, high-sensitivity detectors, and integrated light sources. Strong electromagnetic fields can be created around metallic nanoparticles or in gap of nanostructures, where the local state density of radiating mode is then dramatically enhanced. While enhanced fluorescent emission has been demonstrated in many metallic nanoparticles and nanoparticle pairs, simultaneous mediation of absorption and emission processes of fluorescent emitters remains challenging in metallic nanostructures. Here, we investigate fluorescent emission mediated by metal-dielectric-metal fishnet metasurface, in which localized surface plasmon (LSP) and magnetic plasmon polaritons (MPPs) modes are coupled with absorption and emission processes, respectively. For absorption process, coupling of the LSP mode enables spatially-selective excitation of the fluorescent emitters by rotating the polarization of the pump laser beam. In addition, the polarization-dependent MPP mode enables manipulation of both polarization and wavelength of the fluorescent emission by introducing a rectangular fishnet structure. All the experimental observations are further corroborated by finite-difference time-domain simulations. The structure reported here has great potential for application to color light-emitting devices and nanoscale integrated light sources.

The diffraction of electromagnetic waves at the surface periodic structures accompanied by strong anomalous effects in different diffraction orders is considered in detail for high-contrast interfaces. We restrict discussion by the transverse magnetic polarization of the incident wave (the magnetic field is orthogonal to the plane of incidence) and the simplest geometry when the plane of incidence is orthogonal to the grating grooves. The most attention is devoted to the strong maxima and minima of the energy flux density accompanying specific grazing propagation of some diffraction order. Relation to other anomalies, both Rayleigh and the resonance ones is discussed as well.

A phenomenological analysis of the experimental phase states of the DyMnO3 ferroelectromagnet with a modulated spin structure in magnetic fields along the X, Y, and Z axes was carried out, taking into account the fourth-order magnetic anisotropy. The possibility of a polarization flop (i.e., reorientation of the direction of electric polarization) is explained only in cases of a magnetic field direction along the X and Y axes. The relative values of the fourth-order magnetic anisotropy parameters consistent with measurements of magnetic moments are found.

Electronic absorption bands of conjugated linear carbon chain molecules, namely polyynes H(C $\equiv$ C) $_n$ H ( $n$ =5-7), are exploited to devise light-polarizing films applicable to the UV. Laser ablated polyynes are separated in size and dispersed in a film of polyvinyl alcohol (PVA), which is stretched to align the trapped linear polyyne molecules inside. As a nature of the structural anisotropy, transition dipole of the UV absorption for polyyne molecules is in parallel with the molecular axis and the absorption occurs only for the electromagnetic wave having the amplitude of its electric vector along the molecular axis. Aligned and fixed orientationally in the solid PVA film, polyyne molecules act as selective absorbers of one of the polarization components of incident light at particular wavelength. Using a light source of linearly polarized UV light, whose direction of polarization is rotatable, angular dependence of the absorption intensity is investigated for the stretched PVA film containing aligned polyyne molecules and analyzed in terms of an order parameter in the theory of linear dichroism.

The all-dielectric metasurface-based color filter (CF) has attracted huge interest in many fields due to its excellent optical properties. We present four metasurface-based CFs with different shapes on quartz substrates to generate blue (B), green (G), and red (R) spectra with high color purity. CFs show the maximum reflection intensities of 99.6% (B), 99.7% (G), and 95.1% (R), and their spectra bandwidths are 14, 16, and 13 nm for RGB colors, respectively. These proposed metasurface-based CFs possess high color saturation and ultra-narrow bandwidths. In addition, CFs with different shapes show the tunability of color switching and polarization-dependent characteristics. These CF designs will potentially benefit reflective display technologies, and the ultrahigh color filtering characteristics of CF-1 and CF-2 are particularly useful for high-resolution color printing and micro-LED. Moreover, the polarization-dependent characteristics of CF-3 and CF-4 make it possible for them to be applied as polarization switches, tunable color switches, and so on.

We present the branching fractions for the rare semileptonic decay B→ωl+l− for l=e,μ,τ. The necessary transition form factors are computed in the entire range of momentum transfer within the Standard Model framework of Covariant Confined Quark Model with built-in infra-red confinement. We further compute different physical observables such as forward backward asymmetry, longitudinal and transverse polarization along with other angular observables.

The effects of target thickness on the shape of the bremsstrahlung energy spectrum in Pb for 89Sr beta particles are studied in the photon energy region of 1–100 keV. The thicknesses of the Pb targets chosen for present study are 53, 223, 552, 677, 908 and 1352 mg/cm2. The bremsstrahlung energy spectrum, only at target thickness of 677 mg/cm2 is found to be closer to the Avdonina and Pratt (1999) theory for total bremsstrahlung with the variation of +3%, −2%, +2%, −13%, −39% and 69% at 1, 4, 10, 30, 60 and 100 keV, respectively. The polarization bremsstrahlung is limited up to a particular target thickness at low-energy region, suppressing the bremsstrahlung at high-energy region.

Concentration of band electrons and holes induced by multiphoton ionization in the filament of a femtosecond laser pulse with a diameter of 10 µm before and near the Gaussian waist in nonlinear crystals corresponds to 1018 − 1021 cm−3. Such level of the induced electron-hole polarization component makes an additional contribution to increasing the harmonic generation efficiency in the interaction of femtosecond radiation with nonlinear crystals.

The analytical investigation of the effect of collisions on the Jeans instability in dusty plasma is carried out to observe the effect of the simultaneous presence of polarization force and charge gradient force on the dust particles. The dispersion relation, the instability growth rate and the graphical analysis shows that the combined effect of the charge gradient force, dust polarization force and collisions moves the system towards stabilization.

In this work, a flexible type electromagnetic microwave absorber working in tri-band (i.e) GPS, Wi-Max and WLAN applications are designed and evaluated the prototype model. The electromagnetic microwave absorber consists of 5x5 array of rectangle metamaterial structures which showing the absorption rate of above 90% respectively. Moreover, the absorbers showing high absorption response value by changing its angle of incidence up to 60° in TM and TE polarization. In addition, due to the adaptability of the substrate absorbers implement the bending angles (15°, 30°, 45°, 60° and 90°) with various radius with slight various in the absorption values. The absorber is designed and fabricated and reading are carried out in both planar and conformal manner in which it was observed that the rectangular metamaterial absorber having high absorption value. Along, with the absorption rate the metamaterial characteristics of the absorber and return loss of rectangular metamaterial absorber also evaluated. The proposed metamaterial absorber is fabricated and measured using ANRITSU-MS2037C combinational analyser. The work demonstrates absorbers application to particular radar cross section reduction for WLAN, Wi-Max and ISM applications.

The the polarimeter upgrade program at the Nuclotron internal target is presented. This polarimeter is intended for polarization experiments to study of the spin structure of two- and three-nucleon systems. The simulation of the pd-elastic and pp-elastic scattering for 500 - 1000 MeV proton energy to optimize the experimental setup and the first test of new detectors are performed.

We propose a polarizing interferometer based on a crystal anisotropic medium with variable thickness. The results of experimental simulation modelling show that this interferometer can be used to measure the coherence time in a wide time range from a few femtoseconds to tens of picoseconds. This can be used, for example, to control the picosecond pedestal of spectrally limited femtosecond pulses.

The proton's electric GEp(Q2) and magnetic GMp(Q2) form factors (FFs) are fundamental quantities in nuclear and elementary particle physics. However, the inconsistency in the results on these FFs and their ratio μpRp=μpGEp/GMp as measured using the conventional Rosenbluth separation method, and the polarization transfer (PT) method suggested a systematic difference between the two techniques. To reconcile these measurements, several studies suggested that missing higher order radiative correction to the electron-proton elastic scattering cross section σR(e, Q2), and in particular two-photon exchange (TPE) corrections should be applied. While several analyses were performed to extract the TPE contributions, the most direct technique for measuring TPE is the comparison of electron-proton and positron-proton elastic scattering. In this study, I present a new extraction of the e± elastic scattering cross-section ratio Re+e− as determined using a new parametrization of the TPE corrections. I then compare my results to several previous phenomenological extractions, TPE hadronic calculations, and existing world data on the ratio Re+e− emphasizing mainly the recent high-Q2 measurements from the CLAS, VEPP-3 Novosibirsk, and OLYMPUS collaborations.

Analytical solution for mode-III linearly varying polarization saturation (PS) model in semipermeable piezoelectric me- dia is presented. An infinite arbitrary polarized piezoelectric domain weakened by a center crack is considered for the study based on linearly varying polarization saturation model. For the analysis, an out of plane mechanical and in-plane electric displacement loadings are applied on the boundaries of the infinite domain. After mathematical formulation using complex variable and ex- tended Stroh's formalism approach, the problem is reduced into simultaneous non-homogeneous Riemann-Hilbert (R-H) problems in terms of complex variable functions. Explicit solutions for fracture parameters such as saturated zone length, crack sliding dis- placement (CSD), crack opening potential (COP), local stress intensity factor (LSIF), electric displacement intensity factor (EDIF) and normalize energy release rate (G∗) are derived after obtaining the solution for the R-H problems.

We perform multipolar analysis of second-harmonic generation (SHG) from gallium arsenide (GaAs) nanoantennas grown along different crystallographic directions and discuss their specifics. In particular, analysis of the nonlinear response of nanoantennas grown along the (110) axis based on the Lorentz lemma shows that such nanoantennas generate multipoles with only odd azimuthal index m. This feature of (110)-GaAs nanoantennas provides the best forward/backward directivity as compared to their (100) and (111) counterparts. Using numerical modeling we determine parameters of the cylindrical nanoantenna to achieve optical switching in the nonlinear regime by rotating the pump polarization. We then experimentally demonstrate the nonlinear switching between forward and backward SHG emissions from (110)-grown GaAs nanodisks. ISSN:0094-243X ISSN:1551-7616

Broadband terahertz polarizers based on one-dimensional metal grids on carrying thin-film polymeric substrates of different thicknesses were manufactured by photolithography and investigated with terahertz time-domain spectroscopy (THz-TDS). Polarizers patterned on 4 µm polypropylene (PP) showed the best maximum power transmission >98%. Two 4-μm-PP polarizers assembled as a tandem structure exhibited minimum power transmission 10000:1 which exceeded the dynamic range of THz-TDS. The developed polarizers were used to investigate polarization characteristics of the THz-TDS system.

Terahertz time-domain spectroscopic polarimetry (THz-TDSP) method was used to experimental study polarization properties of unaligned single-wall carbon nanotube thin films with different geometric parameters on transparent float glass substrates in a frequency range from 0.2 THz to 0.8 THz (corresponding to a wavelength range from ~1.50 mm to ~0.37 mm) ata controlled room temperature of 291–293 K, and a relative humidity of 40–45 %. Frequency dependences of azimuth and ellipticity angles of a polarization ellipse of electromagnetic waves transmitted through the samples were obtained for values of 0.2 Wcm−2, 0.6 Wcm−2, and 1.0 Wcm−2 of an external 980 nm optical pumping, with an external static magnetic field of ~0.3 T. Polarization properties were calculated from temporal waveforms of signals transmitted through the samples at the parallel and the crossed by 45° positions to a transmission direction of the polarizers. A change of 15° in the azimuth angle, and of 10° in the ellipticity angle was achieved. The results show that by using carbon nanomaterials-based structures it is possible to devise efficient and affordable magneto-optically tunable polarization modulators that can be used in the advanced areas of terahertz nanophotonics.

A bi-layered chiral metamaterial working in the microwave regime is reported and their constitutive parameters such as chirality and refractive index are obtained for circularly polarized electromagnetic waves based on parameter retrieval procedure. Chirality computation reveals the strong circular dichroic regimes of the proposed MTM and designed chiral MTM shows left-handed behavior for right and left circularly polarized waves. The present study is useful for the realization of polarization devices at microwave frequencies.

AlxGa1-x N/GaN deep ultraviolet LEDs faces significant efficiency droop issue. The factors responsible for the efficiency droop are Shockley Read Hall recombination (SRH), Auger recombination (AR), electron delocalization and electron leakage. The SRH, Auger and electron leakage are functions of carrier concentration and temperature. AlGaN/GaN heterostructure has polarization electric field at interface. In this work we investigate effect of polarization electric field on efficiency droop. It is shown that polarization field enhances Auger coefficient resulting in more droop in efficiency of LED. Thus, for improvement in efficiency polarization field required to be minimized.

We calculate uncertainty budget of a developing thulium optical lattice clock. We estimate necessary level of control over various experimental parameters to achieve total systematic uncertainty of better than 10−17 in fractional units. We show, that clock transition frequency is insensitive to an ambient temperature, as well as quadratic Zeeman shift when interrogating two transition between different hyperfine levels. The optical lattice shift of the clock transition frequency is below 1 mHz for the lattice laser frequency stability of better than 3 MHz around the magic wavelength and relative fluctuation of the lattice polarization and a bias magnetic field of less than 1 mrad.

Chiral Metamaterials (CMMs) are the artificial sub-wavelength electromagnetic composites which show giant optical activity and strong circular dichroism. In this work, we realize a 2-D chiral MTM formed by C4 symmetry semi- circular patterns at terahertz (THz) frequencies. Optical activity such as the pure rotation, ellipticity, circular dichroism are computed numerically. We anticipate that the chiral properties of proposed MTM are useful for the realization of THz polarization devices.

A simple design of circular photonic crystal fiber (CPCF) filled with plasmonic nano rods is presented. The polarization characteristics and spectral losses of the proposed layout are examined using the Full - Vectorial Finite Element Method (FV-FEM). The reported design has the advantage of: highly form surface plasmon polariton (SPP) modes and highly polarization-dependency between the two guided quasi-modes. The polarization features of the CPCF can be enhanced by stuffing the air hole cladding. with several nano rods. The reported novel. structure can be used for filter design. It is found that at λ=0.85 µm, the quasi-TE mode loss. is equal to -10.02 dB/mm whereas it is only –15.01 dB/mm for the single.metal rod TM mode. On the other hand, the incensement of the losses for double nano rods is equal to-69.21 dB / mm for quasi-TE mode and -14.19 dB / mm for quasi-TM mode at λ=0.8 µm.

The study is devoted to the phenomenon of the selective all-optical magnetization switching in multilayered plasmonic structures with GdFeCo. Our recent works showed the possibility to address magnetization state of the single layer of the multilayered structure depending on the polarization of the femtosecond pulse. Here we focus our attention on the other interesting phenomenon – magnetization-selective switching arising from the difference of the magnetization reversal thresholds for the similar femtosecond pulse characteristics but different initial magnetization states of the layers.

In this paper, we studied the dynamic stability of calcium sulphide hexagonal monolayer form after obtaining the electronic properties including state density and electronic band structure. The electronic band structure offers the features of materials electronic properties, providing the indirect 3.21eV band gap. In the presence of parallel and perpendicular polarization, we also explored the optical properties of single-layer calcium sulphide (CaS) where we acquired dielectric function, refractive index, loss function, reflectivity, spectra of absorption and extinction index. In this study, we noted the single-layer anisotropic optical behavior with regard to the parallel and perpendicular polarization plane respectively. The dielectric zero point (static) constant of the hexagonal single layer CaS is 1.82 and 1.35, and the refractive index is 1.95 and 1.54 for cases of parallel and perpendicular filed polarization. The reflectivity at zero frequency is 3.5 percent and 2 percent for both the polarization at which it stays almost continuous about 0.31eV, the lower value of the reflectivity and the absorption coefficient in the partly visible and ultraviolet energy range gives data that the material is transparent in this range, so that single layer CaS is promisingly applied in anti-reflection coefficients.

The dispersion plays an important role in pulse propagation in an optical fiber. The effect of higher order dispersion terms are generally neglected for pico second pulse propagation. In this paper we have tried to discuss the propagation length upto which the third order dispersion (TOD) parameter may be neglected. Beyond this length the ignorance of this parameter is not possible as it may affect the pulse shape. Semiconductor Bloch equations are applied to determine the Polarization induced in the medium due to incident Gaussian pulse. The analysis of induced polarization is made by Non linear Schrodinger equation. To represent the pulse propagation behavior linear partial differential equation is used. The results of the numerical calculations provide a support for the fact that the third order dispersion parameter in an optical fiber may be neglected only upto a specified length depending upon the input pulse width.

In the presented work we theoretically demonstrate that it is possible to asymmetrically (chirally) couple circularly polarized transitions in an atom by interfacing it with the nanostructure. We find that by making use of a quite simple plasmonic structure made of two asymmetric dipole scatterers, it is possible to achieve a very strong asymmetry in the interaction between the transitions, and this asymmetry leads to the observable atomic spin polarization even under external continuous wave pumping such that the total local field at the atomic position has a linear polarization.

The objective of this work is to minimize the reflection losses in order to increase the efficiency of solar cells by using an Anti-Reflection coating (ARC). In this paper, we have analyzed the reflectivity of double layer ARC (DLARC) in the solar cells by finding low reflectance for various substrate materials such are GaAs, AlGaAs, GaInP, Silicon and Cadmium Selenide with single ARC MgF2/TiO2 and various ARCs such as SiO2/TiO2, MgF2/ Si3N4, MgF2/TiO2 with on GaAs substrate at normal incidence. TE& TM mode polarization in the visible and near IR region is also studied. It is found that zero reflectance occurs at 600 nm at normal incidence. This minimum reflectance can be evaluated for various angle of incidence. Here it is continuously maintained up to the angle of incidence 80° at TE &TM mode. It retained zero reflectance from 20° to 60°. It was found that DLARC has considerable effect on the performance of solar cell as compare to SLARC. Furthermore, it was observed that the Reflectivity decreases significantly for MgF2/TiO2 as DLARC. From these investigations, it is concluded that MgF2/TiO2 is one of the most suitable DLARC on various substrate at 400-1000nm range of wavelength & 20°- 60° angle of incidence.

We investigate scattering of a silicon nanoparticle optically isolated from a silicon substrate by a silica layer. We observe characteristic Fabri-Perot behavior of scattering cross section with the increasing of the sublayer thickness. We show that we can independently suppress or enhance the scattering at frequencies of electric and magnetic dipole resonance. Setting a certain angle of incidence and the sublayer thickness, a polarization induced switching between electric and magnetic dipole is achieved. Finally, directivity of scattered radiation is investigated. Regimes with negative angle scattering, conical and upward radiation patterns are observed.

We present a model for calculating the field E(x, y, z, t) which result as a coherent beam combining (CBC) of two beams propagating under a given angle, each being specified by the pulse energy, duration, direction of polarization, carrier to envelope phase, each being focused independently in a common interaction region. We present the main capabilities of the model, estimate CBC efficiency, and show selected results to demonstrate the usefulness of such calculation for experiments to be performed at ELI-NP facility.We present a model for calculating the field E(x, y, z, t) which result as a coherent beam combining (CBC) of two beams propagating under a given angle, each being specified by the pulse energy, duration, direction of polarization, carrier to envelope phase, each being focused independently in a common interaction region. We present the main capabilities of the model, estimate CBC efficiency, and show selected results to demonstrate the usefulness of such calculation for experiments to be performed at ELI-NP facility.

We report here on the reorientation dynamics of the avian Red Blood Cell (aRBC), a structure ellipsoidal in shape and with a non-uniform distribution of birefringence across its diameter. We find that in linearly polarized light, an aRBC shows a dual reorientation behavior with the first reorientation about the major axis and the second about the minor axis so as to align its major axis along the laser propagation direction. We are able to explain the observed sequence of reorientation as a consequence of the minimization of work done in rotating the avian cell first about the major axis and then about the minor axis. These calculations are also used to also show why a single reorientation about the minor axis to reach the final equilibrium position is not seen experimentally. Further, in the case of elliptically polarized light, we see that the second reorientation process about the minor axis of the cell can be controlled by the ellipticity of the polarization of light. We explain this as a consequence of balance between the torques due to birefringence and reorientation.

In the Brewster angle geometry, a multilayer mirror reflects s-polarization component and suppresses the p-polarization componentfrom the incident beam. In the present study a Mo/Si multilayer of d=97A, N=20 layer pairsis used to analyze the polarization characteristics of SR beam of 130A wavelengthat theexperimental station of the reflectivity beamline of Indus-1 synchrotron source. The SR beam polarization characteristics are analyzed at various vertical height at the experimental station. The degree of linear polarization (DOLP) and degree of circular polarization (DOCP) have been evaluated for each vertical height. It is shown that the SR beam at the experimental station of the beamline has 83% DOLP and it gradually decreases with increasing vertical height, on the other hand DOCP increases from 54% to 98%.

In recent years the attention of many researchers is riveted to the study the optical properties of two-dimensional semiconductors such as transition-metal dichalcogenide (TMD or TMDC) monolayers (MLs) which are looking highly promising both from the fundamental point of view and the practical application prospects. The complex band structure and reduced screening coulomb interaction formed there facilitate strong correlation phenomena. These correlation effects in terms of optical response reveal themselves through the specific optical resonances such as excitons, trions, etc., as well as strong optical nonlinearity. In this work we aim to demonstrate some initial steps of comprehensive computational machinery being developed to take into account many-particle effects which are widely observed in a huge number of experiments on TMD MLs conducted at present. As a starting point to describe the corresponding dynamics we address the Heisenberg equation of motion. Processing the quantity of interest we come to an infinite hierarchy of equations. In order to properly truncate this system we use the cluster expansion technique that allows together with several tricks to competently construct some kind of perturbative series for the analyzed equations. Subsequently, these expansions can be treated numerically. In particular, within the current letter we present lower two-particle corrections which contribute to interband polarization.

InxGa1-x N/GaN blue LEDs faces significant efficiency droop issue. The causes of efficiency droop are Shockley Read Hall recombination (SRH), Auger recombination (AR), carrier delocalization and electron leakage. The SRH, Auger and electron leakage are functions of carrier concentration and temperature. InGaN/GaN superlattice has polarization electric field at interface. In this work we explore effect of polarization electric field on efficiency droop. It is shown that polarization field enhances Auger coefficient resulting in more droop in internal quantum efficiency of blue LED. Thus, for improvement in efficiency, polarization field required to be minimized which requires growth of the material in m-plane instead of c-plane.

In this paper we report and analyze development of noncontact trapping of micron-sized particles using optical traps shaped with three-dimensionally structured coherent beam. Trapping fields are generated by interference of laser beams with controllable parameters, including tilt angle, beam waist, polarization state and a number of superposed beams. Visualization and tracking the position of trapped micro-objects in three-dimensional space is realized using axial lensless digital holographic microscopy with real-time computer processing of interferograms.

Circularly polarized photons are widely used for conducting experiments to study magnetic structures of matter. Based on coils developed at Budker Institute of Nuclear Physics (BINP) for a superconducting undulator with a period of 15.6 mm, a model of a superconducting undulator with variable polarization (SCUVP) and a period of 40 mm is proposed. SCUVP consists of two identical superconducting undulators placed mutually perpendicular and powered by currents independently. Depending on different current values in the windings of the undulator, it is possible to create an elliptical undulator with different elliptic coefficients or planar undulators with linear radiation polarization with a zero angle both horizontally and vertically. The paper presents numerical calculations of the undulator fields and its spectra.

Four different varieties of cotton fibers were obtained from farmers and used after cleaning the fibers physically. X-ray powder diffraction data for considered fibers were obtained using imaging plate system (Dip-3200) with dimension 440 x 240 mm2. With the available software, scanning was carried out along the equator to obtain intensity versus two-theta after correcting for instrumental broadening and Lorentz polarization factors. Using peak-fit® program, 6-8 Bragg reflections were identified and Full Width Half Maxima (FWHM) of these reflections (hkl) were used to estimate the crystallite size along [hkl] directions. From these data, we have suggested a novel method to compute crystallite shape for varieties of cotton fibers.

In this study, some selected states of p- and sd-hells namely 10B, 6Li, and 29Si nuclei were conducted, the transvers and longitudinal electron scattering form factors were studied in consideration of the configuration with higher excitation energy above the cores 4He and 16O. When using a microscopical theory, the effect of high-configuration outside the model space (Core-polarization (CP)) is included. Cohen-Kurath interaction for p-shell, Wildenthal’s standard interaction for sd-shell. For core polarization calculations higher energy excitations up to 4ℏω are considering. The addition of CP effects greatly improves the form factors calculations and explains the measured data as dependence of momentum transfer very well.

The metasurface based on gold T-shape nanoantennas array is fabricated and the absorbance spectrum is demonstrated for different orientation of linear polarized light. It is obtained that the plasmonic resonance of absorbance spectrum strongly depends on the polarization orientation. The effect of enhancement of IR vibrational spectrum of a thin layer of organic semiconductor covering the suggested metasurface is studied. For the series of samples of different layer thicknesses (from 5 to 130 nm) the strong effect of SEIRA (surface-enhanced infrared absorption) is demonstrated. Moreover, the special geometry of T-shape structure considered the analyte vibration levels makes it possible to control the light-matter interaction strength by changing orientation of light polarization. The SEIRA effect is discussed in terms of Fano resonance.

To control light by magnetic field magneto-optical nanostructures can be used. Response of well-known periodical structures is narrowband and depending on light's incident angle. In present work we investigated magneto- optical properties of 2D periodic and quasicrystalline structures. These structures consist of gold grating-patterned layer on top of magnetic dielectric film. We showed that in 2D quasicrystalline structures magnetoplasmonic effects, such as the transverse magneto-optical Kerr effect (TMOKE) and Faraday effect, are broadband. Moreover, their independence of light's polarization and incident angle was demonstrated.

Effect of external longitudinal magnetic field on the optical Free Induction Decay (FID) from a free radical was observed for the first time. The experiments were performed on the rotational transition of hydroxyl radical OH (2Π3/2(J=1) ← 2Π3/2(J=0) at 83.8 cm-1) using the Terahertz Free Electron Laser. In contrast to the results of the experiments with a stable paramagnetic molecule NO, the observed effect of external magnetic field on the Free Induction Decay from hydroxyl radicals is more complicated. A longitudinal magnetic field leads to rotation of the polarization plane of the FID radiation, as well as to additional modulation of the signal intensity. The angle of rotation of the polarization plane is large, in agreement with the theoretical predictions. The observed FID kinetics in the time domain are in semi-quantitative agreement with the modeling. This observation opens an opportunity for selective detection by polarization discrimination of weak signals of short-lived reactive paramagnetic free radicals from overwhelming signals that originate from stable non-paramagnetic species.

The coupled amide-I vibrational modes in peptide systems such as fibrillar aggregates can often provide a wealth of structural information, though the associated spectra can be difficult to interpret. Using exciton scattering calculations, we characterized the polarization selective 2DIR peak patterns for cross-α peptide fibrils, a challenging system given the similarity between the monomeric and fibrillar structures, and interpret the results in light of recently collected 2D data on the cross-α peptide PSMα3. We find that stacking of α-helices into fibrils couples the bright modes across helical subunits, generating three new Bloch-like extended excitonic states that we designate A⏊, E∥, and E⏊. Coherent superpositions of these states in broad-band 2DIR simulations lead to characteristic signals that are sensitive to fibril length, and match the experimental 2DIR spectra.

The electromagnon spectrum arising from the Dzyaloshinskii-Moriya (DM) effect in TbMnO3 after a polarization flop is analyzed phenomenologically. Applied alternating electric fields directed along and perpendicular to the spontaneous polarization Px are considered. It is shown that when the electric field is oriented parallel to the spontaneous polarization, the low-frequency electromagnons have two well defined frequencies which depend on temperature. For electric fields perpendicular to the spontaneous electric polarization, the DM mechanism does not excite low-frequency electromagnons in the terahertz range. These results are consistent with available Raman spectrum measurements.

In scalar optics, a spiral phase plate (SPP) spatial filter, independent of its polarity, can perform radial Hilbert transform for isotropic edge enhancement of objects. The same 4f spatial filter setup is also useful to realize multiple-beam interference. However, the polarity of the SPP phase filter can decide the handedness of certain polarization lattice fields created by multiple-beam interference. It is interesting to note that a phase element is exhibiting polarization control on structured fields. We demonstrate this by creating few lattice structures with and without C-point singularities. Experimental and simulation results are presented. The current study may be useful in optical chirality measurement, signal processing, and structured illumination microscopy.

As one kind of special beams, a terahertz (THz) cylindrical vector Bessel beam processes centrosymmetric polarization distribution and nondiffractive propagation properties. Such a vector Bessel beam is potential in various practical applications ranging from THz communication and electron acceleration to sensing and imaging. Here, we propose and experimentally demonstrate a method to directly emit a broadband THz cylindrical vector Bessel (CVB) beam using nonlinear effects. By photo-exciting an indium tin oxide film coated axicon with a circularly polarized femtosecond laser pulse, a high-quality CVB beam is obtained in a broadband THz frequency range. The proposed method is universal and low-cost, opening a simple avenue for the emission of broadband THz specialty beams.