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Developing efficient techniques to realize polarization-independent modulators nowadays is still important for on-chip photonic circuits. Here, we propose and theoretically demonstrate a graphene-based T-slot waveguide modulator, which simultaneously supports the TE and TM polarized modes, offering a greater possibility to achieve the polarization-independent modulation. The modulation performance is comprehensively studied in terms of attenuation loss, insertion loss, modulation depth, normalized mode area, bandwidth and power consumption. Optimizations of key characteristic parameters illustrate that the modulator not only offers a mode confinement beyond the diffraction limit ( MD ) of >0.35 dB/μm, a insertion loss ( IL ) of MD discrepancy of S , C and L bands. Particularly, the modulator possesses a compact footprint of 11.6 μm2, a 3-dB modulation bandwidth of 50 GHz and a power consumption per bit of 2.07 pJ/bit based on theoretical predictions. The polarization-independent operation is also quite robust against the possible fabrication perturbations. Our work may inspire new potential for developing the integrated modulators and opto-electronic interconnects in the advanced polarization-diversity circuits.

Graphene, a two-dimensional monatomic layer of carbon material, has demonstrated as a good candidate for applications of ultrafast photodetectors, transistors, transparent electrodes, and biosensors. Recently, many studies have shown that using metallic deep gratings could enhance the absorptance of graphene of 2.3% up to 80% in the near infrared region for applications in photon detection. This paper presents utilizing a nanograting structure, namely, a compound metallic grating could greatly enhance the absorptance of graphene up to 98% and widen its spectral bandwidth to 0.6 μm, which are greater than those of previous work. The study also showed that the absorptance spectrum is insensitive to angles of incidence. Furthermore, the proposed graphene-covered compound grating might bring a lot of benefits for graphene designs-based optical and optoelectronic devices.

Developing efficient techniques to bridge single-plasmon radiations to nanoscale plasmonic waveguides nowadays is still a critical consideration for on-chip integration of solid-state photonic circuits. Here, we propose and theoretically demonstrate the generation and routing of single plasmons in nanowire-based hybrid plasmonic coupling structures with nanodisk antenna resonators. Optimizations of key characteristic parameters illustrate that the structure not only offers an enhanced tradeoff between the propagation length (∼20 μm) and mode confinement (∼ λ 2/8450), but also exhibits outstanding plasmon generation and guiding properties, such as a Purcell factor of 2.14 × 106, a coupling efficiency from emissions to desired waveguides of 59%, and a Figure-of-Merit of 3 × 107 in the visible and infrared spectral range, which outperforms the previous plasmonic structures. The plasmon emission properties are also quite robust against possible emitter positioning imperfections. Our work may inspire new opportunities in helping design quantum-plasmonic platforms for future quantum information processing and related on-chip plasmonic devices.

Stochastic differential equation of the phase fluctuations is derived for the collision conductive magnetized plasma in the polar ionosphere applying the complex geometrical optics approximation. Calculating second order statistical moments it was shown that the contribution of the longitudinal conductivity substantially exceeds both Pedersen and Hall’s conductivities. Experimentally observing the broadening of the spatial power spectrum of scattered electromagnetic waves which equivalent to the brightness is analyzed for the elongated ionospheric irregularities. It was shown that the broadening of the spectrum and shift of its maximum in the plane of the location of an external magnetic field (main plane) less than in perpendicular plane for plasmonic structures having linear scale tenth of kilometer; and substantially depends on the penetration angle of an incident wave in the conductive collision turbulent magnetized ionospheric plasma. The angle-of-arrival (AOA) in the main plane has the asymmetric Gaussian form while in the perpendicular plane increases at small anisotropy factors and then tends to the saturation for the power-low spectrum characterizing electron density fluctuations. Longitudinal conductivity fluctuations increase the AOAs of scattered radiation than in magnetized plasma with permittivity fluctuations. Broadening of the temporal spectrum containing the drift velocity of elongated ionospheric irregularities in the polar ionosphere allows to solve the reverse problem restoring experimentally measured velocity of the plasma streams and characteristic linear scales of anisotropic irregularities in the terrestrial ionosphere.

Homogeneous, smooth, and partially transparent nanocrystalline thin films of CoFe2O4 were fabricated using a chemical solution approach with additional annealing for 2 h in a temperature range of 300 °C to 600 °C. Structural properties investigated by X-ray diffraction showed a single-phase spinel structure with a random crystallographic orientation for samples annealed above 400 °C. The ferromagnetic nature of prepared films was established from combined substrate with film hysteresis loops measured using a vibrating sample magnetometer. Optical and magneto-optical spectroscopic measurements revealed an improvement in the structural quality of the films after annealing up to 600 °C.

Statistical characteristics of scattered electromagnetic waves in the turbulent magnetized plasma caused by electron density fluctuations are calculated using complex geometrical optics approximation taking into account both diffraction effects and polarization coefficients. Scintillation level normalized on the variance of the phase fluctuations is analyzed analytically and numerically for small-scale plasma irregularities using the experimental data. New properties of the electromagnetic wave scintillations have been revealed. It is shown that splashes arise in the ionosphere leading to the turbulence and generation of new oscillations (waves and/or Pc pulsations) propagating in space and the terrestrial atmosphere. Turbulence extending in the lower atmospheric layers can influence on the meteorological parameters leading to climate change. Web of Science 81 165 159

Using the WIEN2k code, we perform ab-initio calculations of the electronic structure and the permittivity tensor of bcc Fe with magnetization along the [001] and [011] directions. The electronic structure is calculated with various numbers of k -points in the full Brillouin zone and the convergence of the calculated data is being studied. Two exchange-correlation potentials are employed, namely LDA and GGA, and their effect on the outcoming spectra is shown. The permittivity tensor is obtained from the electronic structure by the Kubo formula. From the permittivity tensor the complex spectra of linear ( K ) and quadratic ( G s , 2 G 44 ) magneto-optical parameters are extracted. The spectra are compared to the literature.

Mueller matrix ellipsometry has been used to precisely characterize quartz waveplates for demanding applications in the semiconductor industry and high precision polarimetry. We have found this experimental technique to be beneficial to use because it enables us to obtain absolute and precise measurement of retardation in a wide spectral range, waveplate orientation, and compound waveplate adjustment. In this paper, the necessity of including the optical activity in the Mueller matrix model and data treatment is demonstrated. Particularly, the optical activity of the quartz influences the adjustment of misalignment between the perpendicularly oriented waveplates of the compound biplate. We demonstrate that omitting the optical activity from the model leads to inaccurate values of the misalignment. In addition, the depolarization effects caused by a finite monochromator bandwidth is included in the model. Incorporation of the optical activity to the Mueller matrix model has required a development of rigorous theory based on appropriate constitutive equations. The generalized Yeh's matrix algebra to bianisotropic media has been used for the calculation of the eigenmodes propagation in chiral materials with reduced symmetry. Based on the applied method, the authors have proposed approximated analytical form of the Mueller matrix representing optically active waveplate and biplate and provided discussion on the analytical and numerical limits of the method.

International audience; We present a semi-classical model for spin-injected vertical-cavity surface-emitting lasers (spin-VCSELs) with local optical anisotropies. Particular focus is put on highly-anisotropic spin-lasers with broad application potential. A generalized matrix formalism for extraction of the laser modes is introduced, which enables to calculate spatial distribution of vectorial modes in arbitrary spin-VCSELs. Time-dependence of such laser modes is further studied using the generalized coupled mode theory (CMT). It is the natural anisotropic generalization of the conventional modedecomposition approach. We use the circularly-polarized optical modes as the basis for CMT, which leads to extension of the well-known spin-flip model (SFM). In contrary to conventional SFM, the only input parameters are the geometric and local optical properties of the multilayer structure and properties of the gain media. The advantages of the theory are demonstrated on design and optimization of spin-VCSEL structure with high-contrast grating. We show that the proposed structures can be used for i) polarization modulation in THz range with tremendous applications for future ultrafast optical communication and ii) as perspective compact THz sources.

We extend our layer-by-layer model of photonic eigenmodes (resonance, polarization) of semiconductor laser and VCSELs (Fordos PRA 2017) by considering local optical properties in order to describe the above-threshold lasing even in the multimode regime. Such generalization, consistent with the semi-classical description based on the optical Bloch equations, allows to describe the optical gain and the wave propagation within the cavity in a more realistic way. The formalism is suitable to study the mode competition, since the important physical effects such as spatial-hole burning or cross-saturation mechanisms are included self-consistently. The only input parameters are those describing geometrical and local material properties of the cavity and the gain media, without using any mean-field approximations. We will present our generalized approach for modelling real devices and will show how it can serve in determining the main optical and physical properties of such devices.

The load-bearing capacity of the wire rope is an extremely important factor for the precise rope design. This value mainly depends on the rope cross-section and the strength class. The nominal value of the load-bearing capacity can be found in the standards. However, this value is on the side of safety. For new rope constructions or improvements in production technology, it is suitable to determine the real value of load-bearing capacity. In this paper, we present two approaches, how to determine the real value of the load-bearing capacity related to the single-stranded wire rope. The first approach is based on a simplified experiment using a tensile test. This phase of the research is divided into two separate experiments. The first experiment is focused on tests of individual wires forming the rope. The second experiment is designed to test the entire wire rope. Finally, the second approach uses the finite element method to create a computer model is presented. Since the rope tensile test is a strongly non-linear task, the solver LS-DYNA with an explicit time integration technique is used for simulation of the experiment. The results from both presented approaches are compared With the nominal value. Designed experiment for testing the whole rope and computer modeling method is created based on the practical requirements from industry, and the obtained results will be reflected in the design of new types of wire ropes. Web of Science 25 2 200 192

The Heusler compound Co$_2$MnSi provides a crystallographic transition from B2 to L2$_1$ structure with increasing annealing temperature $T_a$, being a model system for investigating the influence of crystallographic ordering on structural, magnetic, optic, and magnetooptic (MO) properties. Here, we present quadratic magnetooptic Kerr effect (QMOKE) spectra depending on $M^2$ in addition to the linear magnetooptic Kerr effect (LinMOKE) spectra being proportional to $M$, both in the extended visible spectral range of light from 0.8\,eV to 5.5\,eV. We investigated a set of Co$_2$MnSi thin films deposited on MgO(001) substrates and annealed from 300$^\circ$C to 500$^\circ$C. The amplitude of LinMOKE and QMOKE spectra scales linearly with $T_a$, and this effect is well pronounced at the resonant peaks below 2.0\,eV of the QMOKE spectra. Furthermore, the spectra of the MO parameters, which fully describe the MO response of Co$_2$MnSi up to the second order in $M$, are obtained dependend on $T_a$. Finally, the spectra are compared to ab-initio calculations of a purely L2$_1$ ordered Co$_2$MnSi Heusler compound., 4 pages, 3 figures, supplemental pdf, supplemental data files

Functional post-wall waveguides that are formed by periodically distributed dielectric posts are numerically analyzed. In this preliminary study, the propagation constant and attenuation constant of the dielectric post-wall waveguide is rigorously calculated using our originally developed numerical method. The developed formulation is accurate and numerically very fast. Structural parameters of the dielectric post-wall waveguide are properly chosen in order to achieve the confinement of the field in the guiding region as strong as possible even in case of one-layered dielectric structure. The final goal of our investigations is to realize the functional dielectric post-wall waveguide-based filters, which are expected to have a practical application in THz region, where the metallic (PEC) rods are losing their properties.

A mutual coupling of a surface plasmon polariton (SPP) with an optical mode excited in a planar waveguide (WG) is discussed. A planar layered structure is studied consisting of a coupling prism, an Au film and a high-index interlayer for SPPs generation, and a dielectric waveguide composed of a ferromagnetic garnet on a (CaMgZr)-doped gallium–gadolinium garnet substrate (GGG) separated by an air gap. The dependence of coupling resonances on the gap thickness and the interlayer refractive index is analyzed to obtain an optimal field intensity enhancement for future designs of plasmonic and magneto-plasmonic sensing elements.

Purpose The purpose of this paper is to develop a rigorous self-contained formulation for analyzing electromagnetic scattering by grating of plasmonic nanorods. The authors investigate this structure from the viewpoint of the practical application as a refractive index plasmonic sensor. The presented rigorous formulation is accompanied with a neat implementation providing a high computation efficiency and could be considered as an important tool for designing and optimizing compact sensors. Design/methodology/approach Scattering of an incident plane wave by grating made of a periodic arrangement of metal-coated dielectric nanocylinders on a dielectric slab is rigorously investigated using the recursive algorithm combined with the lattice sums technique. As a dielectric slab, the authors consider glass material, which is widely used in experiments, whereas silver (Ag) is used as a low loss metal suitable to excite plasmon resonances. The main advantage of the developed self-contained formulation is that first the authors extract the reflection and transmission matrices of a single planar array from a separate analysis of the grating and the slab and then obtain the scattering characteristics of the whole structure by using a recursive formula. The method is computationally fast. Findings Dependence of the surface plasmon resonance wavelength on the refractive index of the surrounding medium is carefully investigated. The resonance peaks are red-shifted with respect to an increasing refractive index of surrounding medium showing an almost linear behavior. Near field distributions are analyzed at the resonance wavelengths of the spectral responses. Special attention is paid to the formation of the dual-absorption bands because of the excitation of the localized surface plasmons. The authors give physical insight to the coupling between grating and the glass slab. The authors found that a strong enhancement of the field inside the slab occurs when the scattered wave of the grating is phase-matched to the guided modes supported by the slab. Originality/value In the authors’ formulation, they do not use any approximation and it is rigorous and accurate. The authors use their original method. The method is based on the lattice sums technique and uses the recursive algorithm to calculate the generalized reflection and transmission characteristics by grating. Such fast and accurate method is an effective tool apt for designing and optimizing tailored sensors, for e.g. advanced biomedical applications.

The theoretical background to calculate the effective index tuning using the ultrafast electro-optic Kerr effect and a design of slot waveguide geometry are presented. Analysis of the slot waveguide ring resonator with silicon nanocrystals as the active medium to implement the CMOS compatible electro-optic Kerr effect modulator indicates a modulation bandwidth of 51 GHz, therefore, allowing for 90 Gb/s data rate transmission, and a low energy consumption of 22.99 fJ/bit.

The polarization beat length of propagating optical fields in nonlinear birefringent Kerr medium is investigated in the presence of an externally applied DC electric field. We show that the critical power, at which the effective polarization beat length becomes infinite, can be controlled through adjusting the externally applied electric field. The principle of operation is based on modifying the polarization instability by electronically adjusting the effective birefringence through an external electrical bias. The presented analytical expressions describe the beat length and the polarization instability as a function of the applied electric field for an arbitrary optical input state. Web of Science 25 art. no. 104232

In-situ Mueller matrix spectroscopic ellipsometry was applied for monitoring the silicon nanowire growth by plasma-enhanced vapor-liquid-solid method. The technique is proposed as a real-time, non-destructive, and non-invasive characterization of the deposition process in a plasma-enhanced chemical vapor deposition reactor. The data have been taken by spectrally resolved Mueller matrix ellipsometer every 1 min during the 8–10 min long nanowire growth process. We have developed an easy-to-apply optical model to fit the experimental data, which enables to study the evolution of the parameters of the structure during initial stages of the growth. The first results provide information about the effective deposition rate determined from the linear increase of the deposited silicon volume with the deposition time.

A plasmonic Mach-Zehnder interferometer (MZI) for temperature sensing is reported in the terahertz (THz) regime. The MZI is formed by embedding a semiconductor (SC) layer into a silicon membrane, where the SC layer supports two independent propagating surface plasmon polariton (SPP) waves on both surfaces. The temperature-sensitive phase difference between these two SPP waves gives rise to the modulation of the transmitted intensity. The results show that the MZI sensor possesses a sensitivity and a figure of merit as high as 8.9 × 10-3 THz/K and 117, respectively. Theoretical calculations indicate that the further improvement in sensing performance is still possible through optimization of the structure Moreover, an investigation of structural perturbations indicates that the MZI has a good tolerance to the fabrication errors. The compact MZI-based waveguide structure may find important applications in areas of sensing and integrated THz circuits.

A novel amplifier is proposed based on a nanostructured waveguide supporting terahertz waves. A lateral pin photodiode structure, biased with a dc voltage and illuminated by a continuous-wave light, serves as an amplifying medium whereby drifting light-generated electrons provide energy required for amplification. Interaction between the propagating terahertz guided wave and the drifting electron stream is analyzed, and a dispersion equation is derived. Real life parameters of silicon are used to demonstrate and illustrate the achievable performance. Doubling of the wave power over only one micrometer is shown to be feasible even when all loss mechanisms are considered. Web of Science 9 3 art. no. 2200905

This paper deals with extraction of pure Barkhausen noise from the raw signals received in high-frequency regimes. The raw Barkhausen noise signals measured in high-frequency regimes contain components which cannot be attributed to the interaction of Bloch Walls with pinning sites and stress states such as the thermal noise of the sensor and the mechanical vibrations of the sensor-exciting core. Due to the variable ratios of thermal noise to Barkhausen noise as well as distortion of the signal due to vibrations, the raw signal as received and the pure Barkhausen noise signal can differ remarkably, thus making signal interpretation a debatable issue. For this reason, the post-processing method of the measured signal is presented here. In addition, the properties of μScan 500 device are analysed in detail.

Recent technological and scientific interest in spin-polarized vertical-cavity surface emitting lasers (spin-VCSELs) leads to development of advanced laser modeling tools [1]. The models describes arbitrary multilayer structure of spin-VCSELs including general anisotropy of optical properties of individual layers, and also anisotropy of gain. This important generalization allows not only for precise description of static properties of the resonant cavity, but can also be used to precisely calculate effective parameters used in dynamical models. [2] Applications of spin-lasers for high modulation and switching up to GHz/THz frequencies, advanced output beam shape manipulation, and use of active quantum dot structures leads to necessity to model spin-VCSELs with active and passive laterally periodic structures such as gratings, photonic crystals, and diffractive structures. In this paper, we will show the generalization of existing matrix-based models to describe spin-lasers with lateral periodicity. The generalized rigorous coupled-wave analysis (RCWA) will be discussed in details and it will be compared with grid-based techniques such as finite element methods (FEM) and finite-difference time-domain analysis (FDTD). We will also discuss effects of incoherent propagation and random phase during light propagation in the structure. The method will be applied to structures of practical interest consisting of anisotropic grating used for ultrafast laser modulation and photonic structure. [1] T. Fordos, et. al., J. Opt. 16 (2014) 065008, Phys. Rev. A 96, (2017) 043828. [2] M. Drong, et al. Proc. SPIE 10926, (2019) 1092614.

International audience; Spatial properties of pulsed beams become more important in the terahertz range, which causes that reference and sample measurements can differ in the spectral dependent complex phase called the Gouy phase. It originates from propagation of the beam wavefront close to the focus. In such a case, the plane wave approximation has not to be fulfilled and measured data gives incorrect absorptions and dispersions. We present techniques to compensate these phenomena as well as the procedure to achieve the Gouy phase from measured data. Moreover, the model to simulate the Gouy phase detection will be shown in this paper. It gives powerful tool to avoid experimental errors caused by the Gouy phase in terahertz time-domain spectroscopy.

Ahstract— Second-order statistical moments of scattered electromagnetic waves in the turbulent collision conductive magnetized plasma are considered using the modified smooth perturbation method. Diffraction effects, polarization coefficients of both fast and slow waves are taken into account. Numerical calculations are carried out using the experimental data of the ionospheric F-region.

The realization of all-optical AND logic gates for pulsed signal operation based on the photonic bandgap transmission phenomenon is proposed. We are using realistic planar air-hole type coupled photonic crystal waveguides (C-PCWs) with Kerr-type nonlinear background medium. The novelty of our analysis is that the proposed AND logic gate operates with the temporal solitons, which maintain a stable envelope propagating in the nonlinear C-PCWs, enabling true ultrafast full-optical digital signal processing in the time-domain. The bandgap transmission takes place when the operating frequency is chosen at the very edge of the dispersion curve of one of the supermodes in the C-PCWs. In this regard, our original fast and accurate method is used to efficiently calculate the supermodes of the C-PCW system. The underlying semi-analytical full-wave modal analysis is based on the evaluation of the lattice sums for complex wavenumbers using the transition-matrix method in combination with the generalized reflection-matrix approach. As a proof of concept successful pulse operation of the all-optical AND logic gate is demonstrated in the framework of extensive full-wave finite-difference time-domain electromagnetics analysis.

Spin-polarized lasers such as spin-polarized vertical-cavity surface-emitting laser (spin-VCSELs) are prospective devices in which the radiative recombination of spin-polarized carriers results in an emission of circularly-polarized photons. Nevertheless, additional linear in-plane anisotropies in the cavity generally lead in preferential linearlypolarized laser emission and to possible coupling between modes. Optimization of room-temperature spinVCSELs thus relies on a proper modeling method and on a good understanding of these anisotropies that may reveal (i) a local linear birefringence due to strain fields at the surface or (ii) a birefringence in quantum wells (QWs) due to phase-amplitude coupling originating from the reduction of the biaxial D2d to the C2v symmetry group at the III-V ternary semiconductor interfaces. We present a novel method for the modeling of steady-state and dynamical properties of generally anisotropic multilayer semiconductor lasers containing multiple QWs active region. In order to solve the dynamical properties of spin-VCSELs, we combine here optical Bloch equations for a 4-level system with the scattering-matrix formalism, which treats VCSELs as a multilayer structure containing classical active dipole layers [T. F¨ord¨os et al., Phys. Rev. A 96, 043828 (2017)]. The method is then demonstrated on real semiconductor laser structures with InGaAs/GaAsP quantum wells. It is used for calculation of the laser resonance condition, the polarization properties of eigenmodes, the electromagnetic-field distribution inside the laser cavity, and time-dependent properties of the emitted light.

Lateral spin devices are an important concept in nowadays all-metallic spintronic devices. One of the key problems is to obtain large spin injection and detection efficiency. Several concepts has been envisaged, such as to use half-metallic ferromagnetic electrodes or spin-polarized interface barriers. Within this work, we address the optimization of spin devices (namely optimization of spin current density, spin current and spin accumulation) based on adjustment of the geometry (dimensions) of the lateral device, material selection of spin conductors, jointly with optimization of the interface resistance.

Dispersion of the plasmonic behavior at an interface between a dielectric and a conducting medium (e.g. metal, doped semiconductor, graphine, or superconductor) is studied considering the free electron gas in the conducting medium be moving along the interface. The derivation of the dispersion equation is provided, including the damping and the electrons drift. It is shown that the electrons behave as a compressible gas giving rise to new features and new surface plasmon wave solutions of the dispersion equation. A normalized form of the derived dispersion equation is obtained. It is then employed to study the general properties numerically using typical semiconductor material parameters found recently experimentally. Results are discussed in the light of possible novel applications of these physical effects such as, for example, plasmons propagation loss compensation.

Scattering of light by metal-coated dielectric nanocylinders periodically distributed along a cylindrical surface is investigated both theoretically and numerically. The structure is under the authors' interest because of its practical application in design and fabrication of plasmonic devices such as plasmonic ring resonators, Plasmonic Crystals and THz waveguides. The method is based on the T-matrix approach and the field expansion into the cylindrical Floquet modes. The method is rigorous, straightforward and can be easily applied to various cylindrical configurations with different types and locations of the excitation sources. Scattering cross section and absorption cross section of three and four silver (Ag) coated-dielectric nanocylinders periodically situated along a cylindrical surface are studied. Near field distributions are investigated at particular wavelengths corresponding to the resonance wavelengths in the spectral responses. Special attention is paid to the unique and interesting phenomena characterizing the cylindrical structure composed of the metal-coated nanocylinders such as: a ) localization of the field at the outer and inner interfaces of the metal-coated nanocylinders; b) excitement of the field in the gap region between the nanocylinders through the coupled plasmon resonance and c) strong confinement of the field inside the cylindrical structure. Detailed investigations have shown that unique phenomena characterizing the cylindrical configurations of the nanocylinders can be realized using a relatively simple structure composed of three nanocylinders and there is no need to further increase a number of the scatterers (nanocylinders).

In this paper we present importance of depolarization effects modeling to fit spectroscopic Mueller matrix ellipsometry data. The relevant theoretical background based on Mueller matrix formalism is presented. The sample of SiO2 layer (approx. 1μm thick) on silicon substrate is used to demonstrate depolarization effects in obtained experimental data. In the first step the presence of interferences in the layer is used for modeling of depolarization effects caused by finite spectral resolution of the Mueller matrix ellipsometer. In the next step the depolarization caused by focusing of the probe light is analyzed and modeled. Both finite spectral resolution and beam focusing is a common issue in the optical characterization of samples with lateral dimensions smaller than (commonly used) collimated beam. Therefore to fit experimental data with model it is important to assume those depolarization effect into model.

In this paper the Mueller matrix ellipsometry in the spectral range from 0.73 to 6.4eV measured using dual rotating compensator ellipsometer RC2 (Woollam company) is applied to study anisotropic crystals. First we summarize the effects of optical anisotropy to Mueller matrix spectra. As an example of an uniaxial sample we have characterized a Rutile (TiO2) tetragonal crystal. The optical axis of the sample is parallel to its surface. The sample is characterized at variable angle of incidence and variable azimuthal rotation angle. The Mueller matrix spectra are fitted to the model based on Kramers-Kronig consistent Basis spline and obtained optical functions are compared with tabulated data and ab-initio models based on first-principle calculated electronic structure.

Electrically and optically pumped spin-polarized vertical-cavity surface-emitting lasers (spin-VCSELs) seem to attain improved performance compared to their conventional counterparts. Their dynamical properties are studied mostly in the framework of effective rate equations containing parameters that are difficult to directly relate with fundamental material properties. Consequently, such approaches are not suitable for the precise design and optimization of future spin-lasers with desirable dynamical properties. We propose a method for extraction of dynamics-related parameters for the spin-flip model, which is widely used for the description of spin-laser dynamics. This method is based on the correspondence between robust local computational tools and effective models. A general matrix formalism based on S-matrices and generalized Maxwell–Bloch equations is used to determine approximate values of parameters such as cavity decay rate or birefringence rate. This would allow us to tune laser properties by changing the optical properties of the laser cavities and active media according to our needs. The method is demonstrated on realistic anisotropic spin-VCSEL structures containing a 12-quantum-well InGaAs/GaAsP active region. The potential limitations of already existing effective models are discussed.

In this paper, the authors characterize high-order quartz waveplates in the wide spectral range (from 193 to 1700 nm) using a commercial Mueller matrix ellipsometer RC2-DI-Woollam. They demonstrate that Mueller matrix ellipsometry is a powerful tool to obtain the waveplate retardation in a wide spectral range together with azimuthal angles of optical axes with good accuracy. Moreover, they deal with depolarization caused by a finite monochromator bandwidth, which is included in the model using incoherent averaging of Mueller matrices. The application of Lu–Chipman Mueller matrix decomposition to extract depolarization from data is also demonstrated. Finally, Lu–Chipman decomposition is used to demonstrate the presence of the optical activity in quartz, which one may misinterpret with incorrect alignment of the waveplate azimuth angle.In this paper, the authors characterize high-order quartz waveplates in the wide spectral range (from 193 to 1700 nm) using a commercial Mueller matrix ellipsometer RC2-DI-Woollam. They demonstrate that Mueller matrix ellipsometry is a powerful tool to obtain the waveplate retardation in a wide spectral range together with azimuthal angles of optical axes with good accuracy. Moreover, they deal with depolarization caused by a finite monochromator bandwidth, which is included in the model using incoherent averaging of Mueller matrices. The application of Lu–Chipman Mueller matrix decomposition to extract depolarization from data is also demonstrated. Finally, Lu–Chipman decomposition is used to demonstrate the presence of the optical activity in quartz, which one may misinterpret with incorrect alignment of the waveplate azimuth angle.

The motivation of this paper is to determinate the precise complex refractive indices dispersion of ethanol, methanol, and their solutions in the wide spectral range from 8 to 40 000 cm−1 (wavelength range from 250 nm to 1.25 mm) in coupling to biosensors applications (body liquids analyses, tissue ethanol solutions testing, etc.) because a specification of the complex optical functions consistent with Kramers–Kronig dispersion relations in the whole mentioned spectral range was still missing. A general method combining UV/visible/near-infrared spectroscopy and Mueller matrix ellipsometry, Fourier transform infrared spectroscopy (FTIR), infrared attenuated total reflection (ATR) spectroscopy, and terahertz time-domain spectroscopy (THz-TDS) is proposed. The experimental data are modeled using a dielectric function parametrization based on the Brendel–Bormann oscillators.

International audience; Abstract:A surface plasmon resonance (SPR) in terahertz range is demonstrated in InSb. Using an Otto configuration, the surface plasmon is excited on the interface between semiconductor and a thin polymer film by silicon prism. Due to the low effective mass of InSb it is possible to tune SPR by an external magnetic field in transversal configuration. It is possible to achieve resonance shift up to 100 GHz with magnetic field 0.25 T. The experimental results show good agreement with the theoretical model.

This study is aimed at the evaluation of THz gain properties in an optically pumped NH

A robust fiber-optic interferometer, which is formed by introducing two bends (i.e., z shape) to the standard telecommunication single mode fiber, is designed and analyzed theoretically and experimentally for the refractive index (RI) sensing. The first (second) bend couples (re-couples) the core (cladding) mode to the cladding (core) modes. The RI-sensitive phase difference between the core and cladding modes gives rise to the modulation of the transmitted intensity. The experimental results show that the z-shaped interferometric sensor possesses an RI sensitivity as high as 196 nm/RIU and fit well with the theoretical predictions. An investigation of the effect of perturbations of bent angle reveals that the sensor possesses relative high sensitivities as the bent angle ranges from 13° to 17° with the difference between the maximum and minimum sensitivities only 2.5% indicating the structure has a good fabrication tolerance to the inaccuracy of the bent angles. In addition, the sensor has advantages of low cost, simple structure, and an ease of fabrication, showing great potential in many sensing applications.

International audience; Spin-laser structures such as spin-polarized vertical-cavity surface-emitting lasers are semiconductor devices in which the radiative recombination processes involving spin-polarized carriers result in an emission of circularly polarized photons. Nevertheless, additional linear in-plane anisotropies in the cavity, e.g., interfacial and surface anisotropies, generally lead to preferential linearly polarized laser emission and to possible coupling between modes. We present Mueller matrix ellipsometric study of non-intentionally doped InGaAs/GaAsP laser structures devoted for optical pumping operations in the spectral range from 0.73 to 6.4 eV in order to disentangle surface and quantum wells contributions to the linear optical birefringence of the structures. The measurement of full 4 × 4 Mueller matrix for multiple angles of incidence and in-plane azimuthal angles in combination with proper parametrization of optical functions has been used for extraction of optical permittivity tensor components along [110] and [110] crystal axis of surface strained layers and quantum wells grown on [001]-substrate. Such spectral dependence of optical tensor elements is crucial for modeling of spin-laser eigenmodes, resonance conditions, and also for understanding of sources of structure anisotropies.

The paper is devoted to the modelling of the magnetic field around magnetized steel rope kinds using the ANSYS software package. The influence of wire cracks on the amplitude distribution of the generated field is specified for two steel rope kinds assuming surface and inner defects. The first rope is characterized by six rope strands where each is completed by 28 wires (two different diameters, 11 thick wires and 15 thin ones), while the second one has a Z-geometry with special cross section of wires located on rope surface. The results show a significant influence of surface defects (more 10 mT) and measurable magnetic flux responses (in the frame some mT) by cracks in the inner wires with 1 mm gaps. The limits for nondestructive testing of demonstrated ropes are described in detail.

International audience