Voigt Configuration Research Articles

Comment on “Surface electromagnetic wave equations in a warm magnetized quantum plasma” [Phys. Plasmas 21, 072114 (2014)

In a recent article [C. Li et al., Phys. Plasmas 21, 072114 (2014)], Li et al. studied the propagation of surface waves on a magnetized quantum plasma half-space in the Voigt configuration (in this case, the magnetic field is parallel to the surface but is perpendicular to the direction of propagation). Here, we present a fresh look at the problem and obtain a new form of dispersion relation of surface waves of the system. We find that our new dispersion relation does not agree with the result obtained by Li et al.

Fine structure of a resonantly excitedp-shell exciton in a CdTe quantum dot

We present a polarization-resolved photoluminescence excitation study of the absorption spectrum of a $p$-shell neutral exciton in a single CdTe/ZnTe quantum dot. We find that the fine structure of the $p$-shell exciton is completely analogous to the fine structure of the $s$-shell exciton, including the selection rules and the effects of a magnetic field applied in Faraday and Voigt configurations. The energy spectrum of the $p$-shell exciton is found to be well described by introducing respective isotropic and anisotropic constants of the exchange interaction between a $p$-shell electron and a $p$-shell hole. The typical values of these exchange constants averaged over several randomly selected quantum dots yield ${\ensuremath{\delta}}_{0}^{pp}=(0.92\ifmmode\pm\else\textpm\fi{}0.16)$ meV and ${\ensuremath{\delta}}_{1}^{pp}=(0.58\ifmmode\pm\else\textpm\fi{}0.25)$ meV. Additionally, we demonstrate that the nonresonant relaxation of the $p$-shell exciton conserves the exciton spin to a very high degree for both bright and dark exciton configurations.

The coexistence of surface magnetoplasmons (SMPs) and bulk magnetoplasmons (BMPs) in SIS waveguide with the Voigt configuration magnetization

The coexistence behavior of surface magnetoplasmons (SMPs) and bulk magnetoplasmons (BMPs) is discussed on a platform constructed by the Semicondutor-Insulator-Semiconductor (SIS) waveguide with the Voigt configuration magnetization. It is found that the coexistence of SMPs and BMPs stems from the nonzero off-diagonal terms of permittivity tensors of the top and the bottom semiconductor materials (SM) claddings which are induced by the external magnetic field. In this case, the impendence of SM for SMPs contains two contributions associated with both the transversal and the longitudinal wave vectors of SMPs. When the impendence matching condition of SMPs exciting in SIS waveguide is satisfied in the propagating band of BMPs, the coexistence of these two modes thus appears. The results show that the forward-propagating SMPs only coexists with the lower BMPs mode, however, the backward-propagating SMPs coexists with the higher BMPs mode when the top and the bottom SM claddings are magnetized by equal amplitude magnetic field but with opposite direction. In addition, the influences of external-magnetic-field intensity, insulator permittivity and waveguide width on the coexisting frequency widths are also presented.

Analytical viscoelastic modelling of whiplash using lumped-parameter approach

A two-dimensional lumped-parameter simulation of the head and neck has been carried out to capture the dynamic whiplash response during rear-end collisions in the sagittal plane. Joint locations are positioned at the instantaneous axis of rotation locations to capture the realistic intervertebral motions of the cervical spine for the 50th percentile male. Rotational viscoelastic joints are defined at each joint using linear stiffness and damping parameters in a Voigt configuration. Lagrangian mechanics is used to derive the whiplash response for a given collision acceleration. An inverse analysis is used to determine the viscoelastic lumped-parameter values based on cadaver whiplash test results. The results of four models are presented, demonstrating the response and influence of stiffness and damping joint parameters for the following models: (1) uniform joint stiffness with no damping, (2) joint stiffness with no damping, (3) joint damping with no stiffness, and (4) joint stiffness and joint damping. The rigid-linkage viscoelastic joint stiffness and joint damping lumped-parameter model is seen to provide quick solution results and good overall results for the head and intervertebral response (peak head x-displacement, y-displacement and rotation within 10, 20 mm and 7.5°) compared with cadaver test results. This model can be easily scaled to accommodate anthropometric differences in occupant height, weight, gender, and posture for the desired collision dynamics. These properties make this rigid-linkage model well-suited for injury assessment and use in head-restraint optimization to minimize injury and improve neck biofidelity in anthropometric test dummies.

Hole-spin pumping and repumping in ap-type δ-doped InAs quantum dot

We have grown high quality p-type {\delta}-doped InAs quantum dots and have demonstrated coherent spin pumping and repumping of a hole spin in a positively charged quantum dot by means of a single-laser driving scheme under a high magnetic field in the Voigt configuration. Modeling of our system shows excellent qualitative agreement with the experimental findings and further explores the performance of the single-laser scheme for spin pumping and re-pumping.

Energy spectra of three electrons in SiGe/Si/SiGe laterally coupled triple quantum dots

We investigate the energy spectra of three electrons in SiGe/Si/SiGe equilateral triangular and symmetric linear triple quantum dots in the presence of magnetic (in either Faraday or Voigt configuration) and electric fields with only the lowest valley eigenstate being relevant by using the real-space configuration interaction method. The strong electron–electron Coulomb interaction, which is crucial to the energy spectra, is explicitly calculated whereas the weak spin–orbit coupling is treated perturbatively. In both equilateral triangular and symmetric linear triple quantum dots, we find doublet–quartet transition of ground-state spin configuration by varying dot size or interdot distance in the absence of external fields. This transition has not been reported in the literature on triple quantum dots. In the magnetic-field (Faraday configuration) dependence of energy spectra, we find anticrossings with large energy splittings between the energy levels with the same spin state in the absence of the spin–orbit coupling. This anticrossing behavior originates from the triple quantum dot confinement potential. In addition, with the inclusion of the spin–orbit coupling, we find that all the intersections shown in the equilateral triangular case become anticrossing whereas only part of the intersections in symmetric linear case show anticrossing behavior in the presence of magnetic field in either the Faraday or Voigt configuration. All the anticrossing behaviors are analyzed based on symmetry consideration. Moreover, we show that the electric field can effectively influence the energy levels and the charge configurations.

Magnetic lenses of surface magnetoplasmons in semiconductor–glass waveguide arrays

Magnetic lenses for surface magnetoplasmons (SMPs) in semiconductor–glass waveguide arrays (SGWAs) under Voigt configuration are proposed and investigated using simulations and theoretical analyses. The focusing and deflection functions of the magnetic lenses for normally incident SMP beams are demonstrated. For tilted SMP beams, the focal spot of the focusing lenses shifts laterally. Furthermore, it moves in the same direction in which the SMP beam is tilted. The focal length of the lenses is inversely related to the strength of the magnetic field. In this study, we provide a flexible method of steering the SMP beam in SGWAs at the THz region.

Anomalous D'yakonov-Perel' spin relaxation in InAs (110) quantum wells under strong magnetic field: Role of Hartree-Fock self-energy

We investigate the influence of the Hartree-Fock self-energy, acting as an effective magnetic field, on the anomalous D'yakonov-Perel' spin relaxation in InAs (110) quantum wells when the magnetic field in the Voigt configuration is much stronger than the spin-orbit-coupled field. The transverse and longitudinal spin relaxations are discussed both analytically and numerically. For the transverse configuration, it is found that the spin relaxation is very sensitive to the Hartree-Fock effective magnetic field, which is very different from the conventional D'yakonov-Perel' spin relaxation. Even an extremely small spin polarization ($P=0.1\%$) can significantly influence the behavior of the spin relaxation. It is further revealed that this comes from the {\em unique} form of the effective inhomogeneous broadening, originated from the mutually perpendicular spin-orbit-coupled field and strong magnetic field. It is shown that this effective inhomogeneous broadening is very small and hence very sensitive to the Hartree-Fock field. Moreover, we further find that in the spin polarization dependence, the transverse spin relaxation time decreases with the increase of the spin polarization in the intermediate spin polarization regime, which is also very different from the conventional situation, where the spin relaxation is always suppressed by the Hartree-Fock field. It is revealed that this {\em opposite} trends come from the additional spin relaxation channel induced by the HF field. For the longitudinal configuration, we find that the spin relaxation can be either suppressed or enhanced by the Hartree-Fock field if the spin polarization is parallel or antiparallel to the magnetic field.

Theory of Wave Propagation in Magnetized Near-Zero-Epsilon Metamaterials: Evidence for One-Way Photonic States and Magnetically Switched Transparency and Opacity

We study propagation of transverse-magnetic electromagnetic waves in the bulk and at the surface of a magnetized epsilon-near-zero (ENZ) medium in a Voigt configuration. We reveal that in a certain range of material parameters novel regimes of wave propagation emerge; we show that the transparency of the medium can be altered with the magnetization leading either to magnetically induced Hall opacity or Hall transparency of the ENZ. In our theoretical study, we demonstrate that surface waves at the interface between either a transparent or an opaque Hall medium and a homogeneous medium may, under certain conditions, be predominantly one way. Moreover, we predict that one-way photonic surface states may exist at the interface of an opaque Hall ENZ and a regular metal, giving rise to the possibility for backscattering immune wave propagation and isolation.

Deterministically charged quantum dots in photonic crystal nanoresonators for efficient spin–photon interfaces

We demonstrate a novel method for deterministic charging of InAs quantum dots embedded in photonic crystal nanoresonators using a unique vertical p–n–i–n junction within the photonic crystal membrane. Charging is confirmed by the observation of Zeeman splitting for magnetic fields applied in the Voigt configuration. Spectrally resolved photoluminescence measurements are complemented by polarization resolved studies that show the precise structure of the Zeeman quadruplet. Integration of quantum dots in nanoresonators strongly enhances far-field collection efficiency and paves the way for the exploitation of enhanced spin–photon interactions for fabrication of efficient quantum nodes in a scalable solid state platform.

Photonic band gap of three dimensional magnetized photonic crystal with Voigt configuration

In this paper, the properties of two types of three-dimensional magnetized plasma photonic crystals (MPPCs) composed of homogeneous magnetized plasma and dielectric with simple-cubic lattices are theoretically studied by a modified plane wave expansion (PWE) method, as the magneto-optical Voigt effects of magnetized plasma are considered. The equations for type-1 structures with simple-cubic lattices (dielectric spheres immersed in magnetized plasma background), are theoretically deduced. The influences of dielectric constant of dielectric, plasma collision frequency, filling factor, the external magnetic field and plasma frequency on the properties of photonic band gaps (PBGs) for both types of MPPCs are investigated in detail, respectively, and some corresponding physical explanations are also given. The characteristics of flatbands regions are also discussed. From the numerical results, it has been shown that the PBGs of both types of three-dimensional MPPCs can be manipulated by plasma frequency, filling factor, the external magnetic field and the relative dielectric constant of dielectric, respectively. However, the plasma collision frequency has no effects on the PBGs for two types of three-dimensional MPPCs. The locations of flatbands regions can not be tuned by any parameters except for plasma frequency and the external magnetic field.

Anomalous D’yakonov-Perel’ spin relaxation in semiconductor quantum wells under a strong magnetic field in the Voigt configuration

We report an anomalous scaling of the D'yakonov-Perel' spin relaxation with the momentum relaxation in semiconductor quantum wells under a strong magnetic field in the Voigt configuration. We focus on the case that the external magnetic field is perpendicular to the spin-orbit-coupling--induced effective magnetic field and its magnitude is much larger than the later one. It is found that the longitudinal spin relaxation time is proportional to the momentum relaxation time even in the strong scattering limit, indicating that the D'yakonov-Perel' spin relaxation shows the Elliott-Yafet-like behaviour. Moreover, the transverse spin relaxation time is inversely proportional (proportional) to the momentum relaxation time in the weak (strong) scattering limit, both in the opposite trends against the well-established conventional D'yakonov-Perel' spin relaxation behaviours. We further demonstrate that all the above anomalous scaling relations come from the unique form of the effective inhomogeneous broadening.

Magnetic field-controlled femtosecond pulse shaping by magnetoplasmonic crystals

Femtosecond-scale magnetic field-controlled shaping of 200 fs laser pulses reflected from a one-dimensional magnetoplasmonic crystal is experimentally demonstrated. Magnetic field-induced modification of the pulse shape is revealed by measuring the second-order intensity correlation function (CF) of femtosecond pulses reflected from the sample. The sign of the magnetic contribution to the CF is reversed within the pulse. Such temporal shaping of the pulses is attributed to modification of the Fano-type surface plasmon spectral response function under magnetization of the sample in the Voigt configuration.

Peculiarities of THz-electromagnetic wave transmission through the GaN films under conditions of cyclotron and optical phonon transit-time resonances

The theory of THz radiation transmission through the film of compensated GaN of cubic modification under action of electric and magnetic fields has been developed. In the THz frequency range, spectra of the dynamic mobility tensor have been obtained for applied steady-state electric fields of several kV/cm and magnetic fields of several T. The spectra of transmission, reflection and loss coefficients have been analyzed for the Voigt configuration used for the applied fields. It has been shown that the transmitted wave becomes elliptically polarized, and the spectra of polarization characteristics such as ellipticity and rotation angle of the large axis of polarization ellipse were investigated under conditions of cyclotron resonance and optical phonon transit-time one. It has been found that, in certain frequency bands, polarization characteristics have the features valid for both resonances. The new optical method based on the analysis of ellipticity and rotation angle spectra is offered for determination of the low-field mobility.

Goos-Hänchen Lateral Displacements at the Interface between Isotropic and Gyroelectric Media

A detailed study on Goos-Hänchen (GH) lateral displacements of the reflected and transmitted waves propagating at the interface between an isotropic medium and a gyroelectric medium in Voigt configuration is presented. After the reflection coefficient and transmission coefficient are derived, based on the stationary phase approach, GH lateral displacements are obtained analytically. The numerical results for a specific gyroelectric medium are also given. It shows that with the existence of an applied magnetic field, the GH effect occurs not only during total reflection but also during nontotal reflection, which is not true for isotropic media. Moreover, due to the nonreciprocal property of the gyroelectric medium, the sign of the incident angle also influences the displacements. Finite-element method simulations have verified the theoretical results.

Modelling of one-dimensional magnetoplasmonic periodic structures by the effective refractive index method

An external DC magnetic field may change the dispersion diagram of periodic structures, so that tunable reciprocal and non-reciprocal plamonic components may be constructed. In this study, the effect of an external DC magnetic field on the dispersion diagram of plasmonic periodic structures will be investigated by the effective refractive index method. Investigations are focused on the Voigt and Faraday configurations, although it can be extended to other configurations. In this regard, the wave equation for both structures is solved, eigenpropagation constants and eigenpolarisation are derived. Then, the effective propagation constant and finally, the dispersion diagram for the Voigt and Faraday structures will be derived. The effect of the bias field is investigated on the aforementioned structures. It is seen that tunable periodic structures can be achieved by the magnetoplasmonic configurations. Different dispersion diagrams can be obtained for different modal waves. For both structures, there is a transmission band for frequencies below the plasma frequency, especially for extremely low frequencies, where in the absence of a magnetic field, wave transmission is impossible. There is no limit on the period of structure, the period of structure in the simulation varies from zero to 1.6λp.

Voigt Airy surface magneto plasmons

We present a basic theory on Airy surface magneto plasmons (SMPs) at the interface between a dielectric layer and a metal layer (or a doped semiconductor layer) under an external static magnetic field in the Voigt configuration. It is shown that, in the paraxial approximation, the Airy SMPs can propagate along the surface without violating the nondiffracting characteristics, while the ballistic trajectory of the Airy SMPs can be tuned by the applied magnetic field. In addition, the self-deflection-tuning property of the Airy SMPs depends on the direction of the external magnetic field applied, owing to the nonreciprocal effect.

Intertwining of Zeeman and Coulomb interactions on excitons in highly symmetric semiconductor quantum dots

We present an experimental study and develop a group theoretical analysis of the Zeeman effect on excitons in pyramidal semiconductor quantum dots possessing the symmetries of the C3v point group. The magnetic field dependence of the emission pattern originating from neutral exciton states is investigated in both the Faraday and Voigt configurations. The Zeeman doublet splitting of the “bright” exciton states varies linearly with the magnetic field strength in each configuration while the intensity of the “dark” exciton transitions exhibit a nonlinear dependence. We demonstrate that these observations originate from the intertwining of the Zeeman and Coulomb interactions, which provides clear spectral signatures of this effect for highly symmetric quantum dots. We uncover a large anisotropy of the Zeeman doublet splittings for longitudinal and transverse magnetic fields, revealing the ubiquitous role of a symmetry elevation in our pyramidal quantum dots. These results suggest that the common description of the Zeeman effect based on effective g factors for electrons and holes must be revised when dealing with exciton complexes.

Tunable surface plasmon polaritons in metal-strip waveguides with magnetized semiconductor substrates in Voigt configuration

The properties of surface plasmon polaritons (SPPs) in a magnetically tunable strip waveguide geometry comprising of a metal film of finite width deposited on a magnetized semiconductor and covered by an isotropic dielectric material were studied in Voigt configuration. The method of lines was used to compute the dispersion relation of fundamental modes, and the dependence of the propagation constant on metal film dimensions, material parameters and biasing magnetic field was considered. The bounded SPPs are nonreciprocal with respect to the direction of the biasing magnetic field, producing a nonreciprocal phase shift of the order of 2–18 rad mm−1 at a wavelength of excitation 1.55 μm. Moreover, controlled propagation of SPP modes and their effective tuning are possible in this strip geometry, which enables the design and development of tunable optoelectronic devices.

Magneto-optical Kerr effect enhancement at the Wood's anomaly in magnetoplasmonic crystals

Magneto-optical Kerr effect enhancement in longitudinal and transversal configurations is systematically studied in one- and two-dimensional magnetoplasmonic crystals based on the nanostructured nickel films. Spectral dependences of magneto-optical effects demonstrate resonant features with the Fano-type lineshape in the spectral vicinity of the Wood's anomaly associated with excitation of surface magnetoplasmons in Voigt and Faraday configurations, respectively.