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Two classical scenarios in space communications can be examined to evaluate the link performance of free space optical communications (FSO). These scenarios include the downlink and uplink between earth ground stations and near earth geostationary (GEO) satellites, as well as between the earth and spacecraft that are located a significant distance from the earth (i.e., one or more astronomical units (AU) away). Deep space is often defined as being more than 0.01 AU, or around 1,500,000 km, from Earth. In the first part of this analytical research, various practical system characteristics for optical lasers, telescopes, transmitters, receivers, and atmospheric disturbances, including absorption and scintillation, are taken into consideration. The simulation outcomes were compared to significant experimental data from DLR & JAXA's OICETS/Kirari-Japan to validate the extended simulation model. Additionally, this work will propose a synthetic effects-based optical turbulence generator in order to deeply investigate atmospheric turbulence disturbances in free-space optical communication systems and support the advancement of artificial intelligence processing-based mitigation solutions. Worth mentioning, the initial outcomes and analytical comparisons demonstrate the preliminary viability of the simulation model for the link budget and scintillation estimation for FSO investigations, which can give deep insight into the development of the proposed testbed prototyping, machine learning-based laboratory measurement system, and enhancement possibility for FSO project design and execution for longand medium-term space mission planning. [ABSTRACT FROM AUTHOR]

We consider the propagation of light in the generalized Born-Infeld-type nonlinear electrodynamics. The speed of light in a uniform electric or magnetic field is not constant and can be described by the effective index of refraction. When the background field is non-uniform, the path of light is bent by the gradient in the index of refraction. We compute the bending angles of light passing the electric field by a Coulomb charge and the magnetic field by a magnetic dipole using the trajectory equation based on Snell's law. In the limit where the classical Born-Infeld parameter is infinite the bending angles reduce to the bending angles from the Euler-Heisenberg Lagrangian. [ABSTRACT FROM AUTHOR]

An efficient scheme for subluminal light propagation in asymmetric multiple quantum wells is investigated. In such a system, the linear absorption facilitated by transparency can be controlled through tunneling voltage instead of laser field. It is found that, by varying tunneling voltage between two wells and a suitable choice of detuning, the width of the tunneling-induced transparency (TIT) can be broadened. At the same time, it has been analyzed that the dispersion properties of the weak probe pulse could be changed from superluminal to subluminal within the TIT window. The proposed work may have fruitful applications in switching devices and quantum information processing at low light levels. [ABSTRACT FROM AUTHOR]

Current surgical resections for Head and Neck Cancers aim for clear margins to prevent local recurrence. However, up to 20% of cases result in positive margins, with secondary surgery increasing the chances of death after 5 years. We envision a MMF endoscope that collects high resolution images using wavefront shaping to scan a 405 nm beam at the fiber tip and collecting fluorescence intensity and lifetime to map tumor margins and detect residual malignant cells. To address the question whether the information contained in the fluorescence and morphology can be used to classify cancer and normal tissues, we used images acquired with a microscope and artificial neural network. Initial findings show promise to separate cancer from normal tissue when training neural networks on FLIM data. Spatial and temporal resolution and required field of view for effective margin assessment are determined. [ABSTRACT FROM AUTHOR]

This research explores the creation of Type II waveguide configurations in diamond using femtosecond laser technology, focusing on the enhancement of light propagation using pin-structures and extensive parameter investigation, offering significant advances in the fields of photonics and quantum sensing. [ABSTRACT FROM AUTHOR]

The work gives the results of mathematical modeling of processes that lie in the basis of the operation of electroluminescent light sources (ELLS) based on powdered zinc sulfide electroluminophores excited by alternating voltage. The propagation of light fluxes in phosphor-dielectric layers is considered depending on their thickness and the volumetric ratio of phosphor — binder, and the absence of an extremum depending on the brightness of the layer thickness is substantiated. It is shown that in case of flexible ELLS based on wire-electrodes, the electric field near the wires turns out to be significantly inhomogeneous, which leads to uneven illumination and unequal rate of phosphor degradation in different regions of the light-emitting layer. It is shown that a change in the design of ELLS together with the use of a rotating electric field to excite the glow, makes it possible to significantly increase the brightness and service life of such emitters. The results of the calculations are confirmed by the data of the experiments. [ABSTRACT FROM AUTHOR]

The photonic crystals (PhCs) are the great platform for developing optical devices in the present miniaturization of integrated circuits. The proposed research is to study the light propagations in the waveguides and cavities created in the one dimensional (1-D) and two dimensional (2-D) PhCs lattice structure. The constructive and destructive light theory is used to design ring resonator, splitter and combiner for the all optical device design. The finite difference time domain (FDTD) and plane wave expansion (PWE) computational methods are used for the investigation of light flow inside the waveguides and cavities. [ABSTRACT FROM AUTHOR]

Semiconductor optical fiber is currently in high demand because of its significant potential in sensors. ZnO is a good material that can support and enhance the performance of fiber optics. The addition of ZnO film on the hetero-core fiber optics with good core size and refractive index can deliver a special outcome based on the power intensity. In this study, comparison between fiber structure is analysed in term of wavelenght and ZnO film coated on hetero-core portion of fiber optics. The optical propagation losses of such structures are simulated using the COMSOL Multiphysics for different wavelengths (1310 and 1550 nm), refractive index, fiber structure (9–50–9 and 50–9–50 µm) and ZnO thickness (10–50 µm). The results show that 1310 nm of wavelength affected the sensitivity of the design structure. Moreover, the transmittance at the output terminal increased as the ZnO thickness increased using 50–9–50 µm. Initial experiment results show that such optical fibers have the potential for sensitivity. The simulation results in this work guide realizing improved performance in practice. [ABSTRACT FROM AUTHOR]

The present paper focuses on a specific method for solving systems of differential equations with application in nonlinear optics. The basic system is presented by two coupled nonlinear differential equations, written in dimensionless form, which govern the propagation of light pulses in optical fibers. The mathematical algorithm is described in detail in the article. The system is analytically solved. The obtained solutions of the equations are in the form of special functions - Jacobi elliptic delta function. They determine the periodical energy exchange between light pulses. The mathematical method can be applied for pulses with arbitrary initial intensities, generalized phase and wave number mismatch. [ABSTRACT FROM AUTHOR]

The generalized coupled nonlinear Schrödinger equation with cubic-quintic-septic and weak non-local nonlinearity describing the signal propagation in an optical fiber has been considered. Four ordinary differential equations have been obtained using traveling wave variables. The considering equations are reduced to the nonlinear ordinary differential equation of the first order and second degree taking into account the compatibility conditions. The general solution of the obtained equation has been found under some constraints on the parameters of the model. [ABSTRACT FROM AUTHOR]

Metasurfaces have an artificial nanostructured interface with a subwavelength thickness that manipulates light by spatially arranging the meta-atoms which are the fundamental building blocks of the metasurface. The anomalous reflection and refraction of light from metasurfaces are modeled by the generalized laws of reflection and refraction. Such laws indicate that the transmitted and reflected light beams can be bent in arbitrary directions in their respective half-space depending on the direction and magnitude of the interfacial phase gradient, as well as the refractive indices of the surrounding media. Since matrix computations or vector analyses are quite powerful tools for simulations of light propagation through and the flux distribution over an optical surface by ray tracing, this paper provides a set of general formulas for the anomalous reflection and refraction vectors of the re-emitted light developed from the generalized laws of refraction and reflection which are similar to the concise formulas for reflection and refraction vectors governed by Snell's law. The vector formulas are functions of the incidence vector, normal vector, and angle parameters of reflection and refraction. The fundamental angular interpolation formula with angles of azimuth and altitude and the rotational angular interpolation formula defined with radial angle and rotation angle to express the unit vectors of the generalized refraction and reflection are used to analyze metasurface refraction and reflection. The new vector formulas should be good tools for optical simulations and designs of planar metasurface solar concentrators in addition to the traditional solar concentrators. [ABSTRACT FROM AUTHOR]

The use of semiconductors, metals, or ordinary dielectrics in the process of fabrication of nanodevices is at the front edge of nowadays technology, exploiting the properties of light propagation and localization at nanometric scale in new and surprising ways. Understanding accurately how light interacts with these materials at the nanoscale is crucial if one is to properly engineer nano-devices. When the nanoscale is reached, light-matter interactions display new phenomena where conventional approximations may not always be applicable and they should be either revised or voided. In this work, we measure the efficiency of second and third harmonic generation from gold nanolayers. The experimental results are compared with numerical simulations based on a detailed microscopic hydrodynamic model that considers different effects playing a role in the nonlinear response, not usually considered by more generic models. The agreement between experimental and theoretical results proves the importance of all these contributions. [ABSTRACT FROM AUTHOR]

A feasibility study of an innovative apparatus for dynamic characterization of materials at intermediate strain rates is presented. The working principle is based on the Split Hopkinson bar, but the wave propagation occurs through properly sized springs. The system is designed to generate and transmit tension or compression waves having a low propagation speed, in order to reduce the specimen strain rate at the impact. At first, a simplified theory is presented for the estimation of longitudinal wave speed in springs as a function of the main engineering parameters of the coil dimensioning. Then, a preliminary sizing of the apparatus is proposed based on basic considerations of wave propagation theory. Finally, a numerical model of a compression test is presented as a proof-of-concept. [ABSTRACT FROM AUTHOR]

We present experiments of microwave transport in planar Vogel spirals arrays of high permittivity dielectric constant. Despite the lack of disorder, wave transport in certain frequency regions is dominated by localized modes. We characterize these modes spatially, and find that in contrary to disorder induced Anderson localization, their radial decay does not only decay exponentially, but some modes are found to decay according to a power law or to a Gaussian profile. Nevertheless, by extracting experimentally the Thouless conductance, we find that the region where these Gaussian and power law modes exist are regions of low Thouless conductance, similarly to what is expected for Anderson localization. This study unveil the rich modal structure associated with these aperiodic point patterns, and pave the way toward a better understanding of wave localization in general. [ABSTRACT FROM AUTHOR]

Metasurfaces are engineered with specific shapes and sizes to interact with light in a unique way. By manipulating the design of the metasurface, it is possible to control optical properties of the surface such as its thermal emissivity. However, thin layers patterning techniques can lead to side-wall angles, thus modifying light propagation within the structure. Here, we introduce a one-mode model that fairly describes the propagation of light in structures with inclined sidewalls. We applied this method to two families of plasmonics resonators: nano Fabry-Perot and coupled nano Fabry-Perot with refractory materials ZrC and tungsten. [ABSTRACT FROM AUTHOR]

Two high-order nonlinear partial differential equations are considered. They are used for describing propagation pulses in optical fibers. The Painlevé analysis for traveling wave reduction of the equations is completed. As a result of Painlevé test the condition on some parameters of the models are obtained. For constructing the exact solution, simplest equations method is used. Periodic and solitary wave solutions are found. [ABSTRACT FROM AUTHOR]

The tremendous developments in the field of communications imposed a new reality that can only be achieved using optical fibers. In this study, a multimode fiber with a numerical aperture of 0.17 and a core radius of 10 µm has been studied at two wavelengths 850 nm and 1300 nm. Devices and fibers operating on the first wavelength are the cheapest in cost and the simplest in design. In terms of the lowest dispersion that can be obtained, the second wavelength is preferable. The mode parameters associated with optical propagation were calculated by using RP Fiber Calculator. The fractional power in the core is about 80% –100% which is very high and making the fiber suitable for practical applications. The intensity profiles of the modes were illustrated and compared with experimentally observed modes. [ABSTRACT FROM AUTHOR]

It is commonly known that optical losses in metal emerges due to the imaginary part of a material permittivity in the visible spectrum. This causes the low quality factors for plasmonic resonators of conventional materials. Nonlinear plasmonics attracts an interest as platform for controlling of light propagation as well as for its enhancement. In this work we demonstrate that stimulated Raman scattering of pump field energetically supports the propagation of plasmons on the surface of nonlinear plasmonic material. Here we solve nonlinearly coupled wave equations for surface plasmon-polariton (SPP) modes in case of stimulated Raman scattering and demonstrate the extension of SPP propagation distance. We believe that Raman-based active plasmonics makes one step closer to the development of efficient plasmonic devices. [ABSTRACT FROM AUTHOR]

Digital image processing requires substantial computations for characterization. It is since the reliable color reproduction can be achieved by establishing the correspondence between the spectral reflectance of the printed surface and the amounts of deposited inks. The processing is implemented by using different mathematical models. Most of the color prediction models engage some mathematical techniques to predict spectral reflectance for a mixture of colorants that are characterized by absorption and scattering during the light propagation. However, few attempts were made to make a model for prediction the colorants values based on an observing spectrum. This work is devoted to application of artificial neural network approach for solving the inverse problem of spectral reflection prediction. This task has been considered unsolvable as it involves solving a system of the linear differential equations, in which the number of unknowns exceeds the number of equations. Our attempt is based on the assumption that the prediction of the initial colorants from spectral data is possible by analogy with the work of the color perception system in humans. The aim of our study is to offer an approach to the framework selection. The model is built in Matlab and shows satisfactory prediction accuracy. [ABSTRACT FROM AUTHOR]

The paper presents the results of an experimental study of an optical discharge plasma obtained by absorbing radiation from a pulsed-periodic radiation of a CO2 laser with a pulse repetition rate of 40 kHz and an average power of 1.6 kW. In order to increase the length of the breakdown plasma the laser beam (diameter 25 mm) was focused in the in an argon subsonic flow by a lens with a focal length f = 254 mm. To visualize the process, we used a FASTCAM SA-Z video camera (Type 480K), exposure time (1.0 µs), and shooting speed of up to 200,000 fps. The conditions for registering an optical scheme varied by using a Foucault knife, diaphragms, and light filters in order to develop optimal methods for obtaining data. The experimental results showed that the plasma dynamics has two successive stages: from the high-speed optical discharge propagation with absorption of radiation behind the laser supported detonation (LSD) wave front to the next less speed stage. [ABSTRACT FROM AUTHOR]

The orientation dynamics of nematic liquid crystals (NLCs) is rotation of the director, i.e. a unit vector representing the preferred direction of orientation of molecules, under the action of elastic forces and an electromagnetic field (EMF). A numerical method for solving the equations of the orientation dynamics is proposed and details of its implementation are discussed. A special attention is paid to coupling of numerical solvers for the orientation dynamics of NLCs and for Maxwell's equations describing the light propagation in an anisotropic non-uniform medium. A numerical solution of the problem of the Fréedericksz transition is compared with its analytical solution, other examples of numerical simulations of physical phenomena in liquid-crystalline media interacting with electromagnetic waves are given. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

This article presents the effects of haze attenuation on Radio over Free Space Optic (RoFSO) transmission system in KLIA Sepang, one of the towns in Malaysia. The haze condition which affects the FSO link transmissions was considered on October 2015 and on October 2017 at KLIA Sepang referring to the reading record of Air Pollution Index (API). In this paper, OptiSystem simulation software is used as a preliminary study before configuring the real RoFSO setup. We model the RoFSO by converting the radio frequency (RF) signal into light where the light source intensity is modulated with the RF signal. RF signal travels through free space while light propagates through fiber optic channel. Single-FSO and fourFSO channels are compared and analyzed in terms of bit-error-rate (BER), received optical power and eye diagram pattern. The results show that the performance of RoFSO with four-FSO channel system in comparison with single-channel has better receiver sensitivity and clear eye diagram. For future work, deploying multiple RoFSO system can fulfil the increasing demand for optimizing the communication bandwidth. [ABSTRACT FROM AUTHOR]

A novel broadband multimode waveguide bend is proposed that supports the propagation of multiple TE modes on a silicon-on-insulator platform. The gradient curvature bend utilizes trapezoidal subwavelength grating (SWG) segments, connected by adiabatically tapered radial strips to achieve efficient mode (de)multiplexing. The inclusion of the radial strips offers an extra degree of design freedom, allowing the realization of a multimode bend with only one single full etch step. The access waveguide has a width of 2.075 μm with an effective radius of 10 μm. Propagation loss for all modes remains below 2.96 dB, and intermodal crosstalk has a maximum of -19 dB across a broad bandwidth of 100 nm, centred at 1550 nm. This work presents an excellent design choice for broadband mode-division multiplexing operations. [ABSTRACT FROM AUTHOR]

Light propagation inside the tissue multilayers has been an issue because of the variation of thickness subcutaneous fat layer. Monte Carlo simulation was studied since it is as gold standard and consists in computational simulation of that chain and in constructing statistical estimates of the desired functional. Four layers of 3-D was quantitatively investigated the relationship between variation thickness of subcutaneous fat layer and measurement of muscle oxygenation using near infrared spectroscopy. The scattering coefficient, absorption coefficient, refractive index and anisotropy factor of each layer were found in the literature. All parameters could be estimated with having different of absorbance less than (2 a.u) for fat thickness 1 mm and 2 mm of human skin in the visible part of the spectrum at 600nm and 900nm. Thus, this result may help us to prove that our human muscle is transparent to this visible and especially near infrared region and might be useful tool for muscle activation studies in the future. [ABSTRACT FROM AUTHOR]

The sensitivity of the oxygenation detection using non-invasive light visible and near infrared range during muscle activation is clinically important. Monte Carlo simulations have been performed to determine light propagation based on epidermal thickness of human skin model. All perimeters such as absorption coefficient, scattering coefficient and anisotropy factor of the five layers samples in the visible spectral range from 600 to 900 nm was determined in this paper. In order to assess the predictability of our simulations, we evaluate their accuracy by comparing results from the model with actual skin measured data. The parameters was estimated using root-mean-squared error of less than 5% for epidermal thickness from (0.001 to 0.2) cm of human skin model under the visible part of the spectrum. The change in optical density is significantly decreased and the linearity of measurement characteristics is clearly distorted by the presence of a larger thickness layer of epidermis about maximum 0.2 cm. Thus, suitable modelling of light propagation passing through epidermis layer in a human muscle is important for quantitative near-infrared spectroscopy and optical imaging for muscle activation studies. [ABSTRACT FROM AUTHOR]

Applications of the diffuse optical tomography to a thyroid cancer detection have been investigated by using the optical contrast. For the application, one needs to investigate effects of two factors (the diffusive reflection and refractive-index mismatch) at the tissue-trachea interface on light propagation in the human neck. In a previous work, the human neck was modeled as a two-dimensional circular heterogeneous medium consisting of a background medium and a circular void region, and the effects of the two factors at the medium-void interface in the simple heterogeneous medium were investigated using the time-dependent radiative transfer equation (RTE) in the time domain (TD). Nevertheless, the effects of the two factors in the continuous wave (CW) is still unclear because a crossover from the ballistic light to diffusive light in the CW differs from that in the TD. In this paper, we investigated the effects of the two factors using the steady-state RTE in the CW for the simple heterogeneous medium. The numerical results showed that the diffusive reflection dominated over the refractive-index mismatch at the medium-void interface even when the void region was located near the light source, where light is scattered anisotropically. The results in the CW were quite different from those in the TD, where the strong effects of the refractive-index mismatch were observed. The difference in the effects between the TD and CW is probably ascribed to a fact the refractive index influences in a shorter time scale compared to the time period for the average in the TD. [ABSTRACT FROM AUTHOR]

We numerically studied light propagation in the two-dimensional human neck model using the time-dependent radiative transfer equation (RTE) for an application of diffuse optical tomography to a thyroid cancer detection. Because complicated light propagation is induced by a heterogeneity of the human neck, highly forward-peaked scattering of light by the tissue volumes except the trachea, and the refractive-index mismatch at the trachea-tissue interface and external boundary, one needs a large number of discrete angular directions (ND) for the RTE calculations, meaning high computational loads. Toward a construction of an efficient numerical scheme of the RTE, in this paper, we focused on a numerical treatment of the highly forward-peaked scattering of light. Then, we investigated numerical errors of the RTE calculations using two kinds of renormalization approaches to the highly forward-directed phase function: the conventional Liu’s approach and developed approach by some of the authors. The investigations showed that the developed approach provided accurate results of the RTE calculations around the peak time regimes even when ND decreased. In the decay time regime, however, the developed approach provided less accurate results because in that regime the refractive-index mismatch at the trachea-tissue interface dominated in the light propagation over the highly forward-peaked scattering. [ABSTRACT FROM AUTHOR]

In this paper we have analysed the existing methods of pest and disease field control on the basis of solar powered equipment and apparatus. The necessity of the presented research came from the considered problem of crop losses and reduction of product quality. We have highlighted the advantages of using the electrophysical method for monitoring the number and type of insect pests. The novel construction of the light trap is a three-ring, three-slot and single-slit for monitoring the number and species of insects, patented in RU85799, RU97245. Single-slit light trap had revealed as the most effective in the field operation so far. We discussed a methodology of the design and development of technical and technological parameters of solar-powered energy-saving electro-optical converter on the base of single-slit light trap. We have also presented the comprehensive analysis of the single-slit light trap structure and analytic methods of calculating the main geometrical parameters including the space volume of light flux propagation. [ABSTRACT FROM AUTHOR]

In the paper is presented a software application that was designed, programmed, realized and tested in order to improve teaching activities in terms of courses, seminaries and laboratories, especially for 3rd year students, from Optometry and Medical Engineering specializations. The software interface is presented as a flexible interface, easy to be used by the students and professors, who allows a more proper and efficient deepening of specialized knowledge, via simulating some processes and optical phenomena. In fact, it is about the phenomena of light radiation propagation through the main basic optical elements (the most used in the construction of optic and medical apparatus and equipments) (the lens, the mirror, the prism). By using such of application for each type of optical element, depending by its technical and optical characteristics, due to the light reflection and refraction, it became possible to be automatically determined all the specific properties of the obtained images through each type of optic elements. Moreover, for a complete simulation and an efficient knowledge deepening, during application running, there is generated the graphical representation of the optic scheme and also related to the way in which the image can be formed through any of the above specified basic optical elements. Currently, the application is being tested and seems to be an excellent solution both for the increasing of the teaching activity and for increasing of attraction of the students reported to the classic teaching methods like different optics problems solving. It was also observed an increase in the degree of understanding among students related to the presented phenomena. The software application presents also an important advantage, namely that it could be used also in case of optical systems design made up of devices with applications in optometry and medical engineering. The proposed solution referring to the software application using for some optical phenomena could be extended also for wider fields, like different physical phenomena or for any technologic processes. [ABSTRACT FROM AUTHOR]

A novel optical design for a flexible SAXS beamline at a modern synchrotron has been implemented for the CoSAXS beamline at the 3GeV ring at the MAX TV Laboratory. The performance of the beamline has been simulated through combined ray tracing and wave propagation with the code xrt taking into account the low emittance and highly coherent beam of MAX TV and the short inter-optics distances of the beamline. The total photon flux is estimated to be 1012-1013 ph/s with the coherent flux portion up to 10 % at 7.1 keV. The inhomogeneities in the X-ray beam arising from use of real (non-idealised) mirror surfaces are also modelled using the measured slope profiles of the mirrors. Strategies to mitigate these inhomogeneities are discussed. The optical components for CoSAXS have been constructed and beamline commissioning will start in 2019. [ABSTRACT FROM AUTHOR]

The EXPERT setup located at the Super-FRS facility, the part of the FAIR complex in Darmstadt, Germany, is intended for investigation of prop- erties of light exotic nuclei. One of its modules, the high granularity neutron detector NeuRad assembled from a large number of the scintillating fiber is in- tended for registration of neutrons emitted by investigated nuclei in low-energy decays. Feasibility of the detector strongly depends on its timing properties defined by the spatial distribution of ionization, light propagation inside the fibers, light emission kinetics and transition time jitter in the multi-anode pho- tomultiplier tube. The first attempt of understanding the pulse formation in the prototype of the NeuRad detector by comparing experimental results and Monte Carlo (MC) simulations is reported in this paper. [ABSTRACT FROM AUTHOR]

ASTRID project, French sodium cooled nuclear reactor of 4th generation, is under development at the moment by Alternative Energies and Atomic Energy Commission (CEA). In this project, development of monitoring techniques for a nuclear reactor during operation are identified as a measure issue for enlarging the plant safety. Use of ultrasonic measurement techniques (e.g. thermometry, visualization of internal objects) are regarded as powerful inspection tools of sodium cooled fast reactors (SFR) including ASTRID due to opacity of liquid sodium. In side of a sodium cooling circuit, heterogeneity of medium occurs because of complex flow state especially in its operation and then the effects of this heterogeneity on an acoustic propagation is not negligible. Thus, it is necessary to carry out verification experiments for developments of component technologies, while such kind of experiments using liquid sodium may be relatively large-scale experiments. This is why numerical simulation methods are essential for preceding real experiments or filling up the limited number of experimental results. Though various numerical methods have been applied for a wave propagation in liquid sodium, we still do not have a method for verifying on threedimensional heterogeneity. Moreover, in side of a reactor core being a complex acousto-elastic coupled region, it has also been difficult to simulate such problems with conventional methods. The objective of this study is to solve these 2 points by applying three-dimensional spectral element method. In this paper, our initial results on three-dimensional simulation study on heterogeneous medium (the first point) are shown. For heterogeneity of liquid sodium to be considered, four-dimensional temperature field (three spatial and one temporal dimension) calculated by computational fluid dynamics (CFD) with Large-Eddy Simulation was applied instead of using conventional method (i.e. Gaussian Random field). This three-dimensional numerical experiment yields that we could verify the effects of heterogeneity of propagation medium on waves in Liquid sodium. [ABSTRACT FROM AUTHOR]

Using COMSOL Multiphysics, we simulate free convection along a pumped active mirror amplifying medium. We study the induced boundary layers and how it affects the wave front propagation. To comfort our simulations, we set up a Mach-Zehnder interferometer to characterize and measure the local variation of air refractive index and temperature. [ABSTRACT FROM AUTHOR]

We present the numerical modeling of two different randomization methods of photonic lattices. We compare the results of light propagation in disordered aperiodic and disordered periodic lattices. In disordered aperiodic lattice disorder always enhances light transport for both methods, contrary to the disordered periodic lattice. For the highest disorder levels, we detect Anderson localization for both methods and both disordered lattices. More pronounced localization is observed for disordered aperiodic lattice. [ABSTRACT FROM AUTHOR]

We investigate optical forces in the time domain, instead of using the time-average Maxwell stress tensor. We demonstrate first that a plane wave causes on a physical object an optical pressure that fluctuates at optical frequency in the time domain. The analytical formula for the optical force dynamics is presented for this case. The case for two-wave illumination with slightly different frequencies is considered next. It is shown that in this case the optical force acquires a component at the beating frequency. The analytical expression for the transient force is deduced and its relation with average force explained in detail. [ABSTRACT FROM AUTHOR]

Light-sheet fluorescence microscopy enables rapid 3D imaging of biological samples. Unlike confocal and two-photon microscopes, a light-sheet microscope illuminates the focal plane with an objective orthogonal to the detection axis and images it in a single snapshot. Its combination of high contrast and minimal sample exposure make it ideal to image thick samples with sub-cellular resolution. To uniformly illuminate a wide field-of-view without compromising axial resolution, propagation-invariant light-fields such as Bessel and Airy beams have been put forward. These beams do however irradiate the sample with a relatively broad transversal structure. The fluorescence excited by the side lobes of Bessel beams can be blocked physically during recording; though at the cost of increased sample exposure. In contrast, the Airy beam has a fine transversal structure that is both curved and asymmetric. Its fine structure captures all the high-frequency components that enable high axial resolution without the need to discard useful fluorescence. This advantage does not carry over naturally to two-photon excitation where the fine transversal structure is suppressed. We demonstrate a symmetric and planar Airy light-sheet that can be used with two-photon excitation and that does not rely on deconvolution. [ABSTRACT FROM AUTHOR]

We present an alternative method to ray tracing that is based on a phase space description of light propagation. Liouville's equation of geometrical optics describes the evolution of the basic luminance on phase space. At an optical interface, the laws of optics describe non-local boundary conditions for the basic luminance. A discontinuous Galerkin method is employed to solve Liouville's equation for a dielectric total internal reflection concentrator. [ABSTRACT FROM AUTHOR]

Light beam propagation through an anisotropic liquid crystal medium is numerically simulated. The Maxwell equations are solved by the FDTD method on computational grids with up to 6 · 108 nodes. Propagation of the fundamental mode HE11 of the fiber-optical light guide through a layer of a nematic liquid crystal filling a transverse gap in the optical fiber and containing a disclination. The behavior of the angular moment as a function of the layer thickness and disclination power is studied. System parameters that ensure the most effective generation of twisted light beams are found. [ABSTRACT FROM AUTHOR]

The paper investigates the influence of an external magnetic field on light propagation through a magnetooptical biaxial, biaxial hyperbolic and anisotropic magnetophotonic crystal. It is demonstrated that the application of a magnetic field results in splitting and reconnection of an isofrequency near the self-intersection point and thus it leads to the disappearance of conical refraction in a crystal. This effect makes it possible to control light propagation by means of a magnetic field. In addition, it is demonstrated that the diffraction divergence of a beam is suppressed in a homogeneous magneto-optical biaxial crystal. [ABSTRACT FROM AUTHOR]

Several possibilities are investigated to control spatio-temporal characteristics of the femtosecond filamentation process and the resulting white-light generation. We controlled the development of self-focusing, and resulting locations of filaments producing white-light in water by changing the transverse spatial phase of an initial Gaussian beam with a computer generated holographic technique and a spatial light modulator. We studied intense femtosecond filamentation and propagation of femtosecond pulses with different transverse modes in water. The filament propagation length was found to increase with Bessel-Gaussian modes of the beams, when more lateral lobes were used, under the conditions of the same peak intensity, pulse duration, and size of the central peak of the incident beam. We also investigated variations of white-light generation when the delay between the two pulses was varied. With a decrease of the relative delay, an enhancement of white-light output was observed, which at near-zero delays was reverted to a suppression of white-light generation. [ABSTRACT FROM AUTHOR]

The technology and methods for remote quantitative imaging of electrostatic potentials and electrostatic fields in and around objects and in free space is presented. Electric field imaging (EFI) technology may be applied to characterize intrinsic or existing electric potentials and electric fields, or an externally generated electrostatic field made be used for "illuminating" volumes to be inspected with EFI. The baseline sensor technology (e-Sensor) and its construction, optional electric field generation (quasi-static generator), and current e-Sensor enhancements (ephemeral e-Sensor) are discussed. Demonstrations for structural, electronic, human, and memory applications are shown. This new EFI capability is demonstrated to reveal characterization of electric charge distribution creating a new field of study embracing areas of interest including electrostatic discharge (ESD) mitigation, crime scene forensics, design and materials selection for advanced sensors, dielectric morphology of structures, tether integrity, organic molecular memory, and medical diagnostic and treatment efficacy applications such as cardiac polarization wave propagation and electromyography imaging. [ABSTRACT FROM AUTHOR]

Reducing the timeline for certification of composite materials and enabling the expanded use of advanced composite materials for aerospace applications are two primary goals of NASA's Advanced Composites Project (ACP). A key a technical challenge area for accomplishing these goals is the development of rapid composite inspection methods with improved defect characterization capabilities. Ongoing work at NASA Langley is focused on expanding ultrasonic simulation capabilities for composite materials. Simulation tools can be used to guide the development of optimal inspection methods. Custom code based on elastodynamic finite integration technique is currently being developed and implemented to study ultrasonic wave interaction with manufacturing defects, such as in-plane fiber waviness (marcelling). This paper describes details of validation comparisons performed to enable simulation of guided wave propagation in composites containing fiber waviness. Simulation results for guided wave interaction with in-plane fiber waviness are also discussed. The results show that the wavefield is affected by the presence of waviness on both the surface containing fiber waviness, as well as the opposite surface to the location of waviness. [ABSTRACT FROM AUTHOR]

Magnetostrictive transduction has been widely utilized in NDE applications, specifically for generation and reception of guided waves for long-range inspection of components such as pipes, vessels, and small tubes. Transversemotion guided wave modes (e.g., torsional vibrations in pipes) are the most typical choice for long-range inspection applications because the wave motion is in the plane of the structure. Magnetostrictive-based sensors have been available for several years for these wave modes based on the Wiedemann effect. For these sensors, a permanent magnetic bias is applied that is perpendicular to the direction of the propagated guided wave. This bias field strains the material that the guided wave is generated in preferentially in the desired particle motion direction. A time-varying magnetic field oriented parallel to the direction of guided wave propagation is also induced in the material. This time-varying field is induced using an electric coil located near the material surface. The interaction of these two fields produces the guided waves; an inverse effect is used for the receive process. An alternative configuration of a sensor for generating and receiving these traverse-motion guided waves is to swap the biasing and time-varying magnetic fields directions. Since transverse-motion guided wave sensors are typically much longer in the particle motion direction than in the bias field direction, the net effect of this alternative design is that the magnetic biasing length is shorter and different coil designs can be used. Because of this, the alternative design, known as a magnetostrictive transducer (MsT), exhibits a number of unique features compared to the Wiedemann sensor described above, such as: 1) the ability to use smaller rare earth permanent magnets and achieve uniform and self-sustained bias field strengths, 2) the choice of more efficient electric coil arrangements to induce a stronger time-varying magnetic field for a given coil impedance, 3) more easily exhibit nonlinear operating characteristics given the efficiency improvements in both magnetic fields, and 4) the ability to generate unidirectional guided waves when the field arrangement is combined with a magnetically soft ferromagnetic strip (patch). MsT designs will be presented that are suitable for different inspection applications, one using electromagnetic generation and reception directly in a ferromagnetic material and another design that integrates a magnetostrictive patch to improve the efficiency and allow special operating characteristics. [ABSTRACT FROM AUTHOR]

Anisotropy is an important property of the transparent ordered solids such as crystals, liquid crystals or polymer foils consisting in the dependence of their physical parameters on the propagation direction and light polarization state. The most common birefringent materials are the crystals (including here the liquid crystals) with asymmetric structures and the plastics under mechanical stress. For uniax materials there is a single direction governing the optical anisotropy (called as optical axis), whereas all directions perpendicular to it are optically equivalent. The uniax materials are characterized by two values of the refractive index. The ordinary value (no) is measured with linearly polarized radiations acting perpendicular on the principal section, while the extraordinary value (ne) corresponds to linearly polarized radiations with their electric field intensity contained in this section [1]. Some results obtained by different methods in estimating the main refractive indices and birefringence of some uniax anisotropy layers are given and a comparative study of the accuracy of the applied methods is discussed in this paper. [ABSTRACT FROM AUTHOR]

When light propagates through a step-index polymer optical fiber (SI-POF) its angular power distribution is influenced by attenuation and scattering. Both influences depend on the propagation angle θz between the ray and the optical axis. However there is an additional dependency on the angle θφ which describes the skewness of a ray. While the skewness of a ray is known to affect attenuation and scattering for that ray, its influence is neglected in common modelling approaches. However the consideration of the skewness is important, since the power distribution in a SI-POF over θφ strongly depends on the launching condition. Furthermore no skewness-dependent attenuation and scattering data are available for SI-POF. We present a measurement setup which allows us to retrieve scattering and attenuation data for SI-POF depending on both θz and θφ along with results that prove the influence of the skewness. The obtained results can be included in a novel propagation model that respects the skewness of a ray. [ABSTRACT FROM AUTHOR]

The pulse propagation in an optical fiber is highly influenced by dispersion and non-linearity. Dispersion length is dependent on the group velocity dispersion (GVD) parameter β2. In this paper we have studied the effect of dispersion on pulse propagationby considering the effect of nonlinearity on β2. The results show that the shape of the pulse is highly influenced by this. The reason for the change in the pulse is due to the change in the dispersion length which results due to change in GVD parameter by considering the nonlinearity. [ABSTRACT FROM AUTHOR]

With the recent scientific advancements in Terahertz (THz) wave propagation and reception technology, there has been significant development in new possibilities for using THz waves - offering new possibilities in THz detection and ranging. A first foundational step toward this goal is to better understand THz transmittance in the turbulent atmosphere. In this project, a frequency modulation pattern of THz waves was created by utilizing a system of shifting frequency based on temperature, air humidity, and distance of transmission. The total path loss of the wave in air, based on the wave spread and molecular absorption, was then modeled using radiative transfer theory, onto a set of JavaHAWK filtered- HITRAN data representative of an air sample. This data was used to generate a path loss matrix, which was then used to optimize frequency of transmission for the specific conditions. The concept to be evaluated is whether adaptive frequency modulated THz might usefully decrease transmission losses by adjusting to atmospheric conditions (such as local variations in temperature and humidity). [ABSTRACT FROM AUTHOR]

We have applied fully- and partially-coherent synchrotron radiation wavefront propagation simulations, implemented in the "Synchrotron Radiation Workshop" (SRW) computer code, to analyse the effects of imperfect mirrors and monochromator at the Coherent Hard X-ray beamline. This beamline is designed for X-ray Photon Correlation Spectroscopy, a technique that heavily relies on the partial coherence of the X-ray beam and benefits from a careful preservation of the X-ray wavefront. We present simulations and a comparison with the measured beam profile at the sample position, which show the impact of imperfect optics on the wavefront. [ABSTRACT FROM AUTHOR]

Commissioning of the first X-ray beamlines of NSLS-II included detailed measurements of spectral and spatial distributions of the radiation at different locations of the beamlines, from front-ends to sample positions. Comparison of some of these measurement results with high-accuracy calculations of synchrotron (undulator) emission and wavefront propagation through X-ray transport optics, performed using SRW code, is presented. [ABSTRACT FROM AUTHOR]