Negative Lateral Shift Research Articles

Posterolateral stabilization of the elbow by autologous ligament reconstruction to limit long-term development of osteoarthritis.

Posterolateral instability is the most frequent form of both acute and chronic elbow instability. Joint incongruity due to posterolateral unlocking leads to shear and compression stress of the internal aspect of the humeroulnar joint. We carried out long-term analysis of patients with posterolateral elbow instability in order to determine whether, in addition to improving their symptoms, reconstruction of the lateral collateral ligament complex may play a protective role against the development of post-traumatic osteoarthritis. We hypothesized that ligament reconstruction according to the technique of O'Driscoll stabilizes the elbow and also limits the development of osteoarthritis in the long term. Patients with symptomatic posterolateral instability of the elbow and who underwent ligament reconstruction according to the technique of O'Driscoll from January 1995 to December 2010 were identified and retrospectively included for 2 follow-up evaluations at a mean of 5 and 14years. Fourteen elbows in 14 patients were included. All had a negative lateral pivot shift test and none reported a new episode of instability. Two patients (14%) had osteoarthritis. The 2 radiographic evaluations showed no progression of osteoarthritis. Osteoarthritis developed in 33% of patients with intra-articular fracture. In simple dislocations, pre-existing osteoarthritic lesions were stabilized and there were no new cases of osteoarthritis. Elbow ligament reconstruction according to the technique of O'Driscoll gives effective posterolateral stabilization and appears to protect against progression to osteoarthritic degeneration in the long term. In the absence of associated lesions, it prevents the development of osteoarthritis or the worsening of pre-existing osteoarthritis.

Controlling optical lateral shifts in a monolayer graphene system

In this letter, we have studied the optical lateral shifts of transmitted and reflected lights in a defect structure doped by a single layer of graphene nanostructure. For adapting the optical features of the lateral shifts, we have first studied the refractive index properties of the defect layer. We have studied the conditions for achieving the negative and positive refractive index of the graphene monolayer system. After that, we have discussed the optical lateral shifts of the reflected and transmitted light beams when the refractive index of the graphene nanostructure become positive or negative, respectively. We have found that the enhanced lateral shifts for reflected and transmitted lights may be possible for a positive refractive index. For the negative refractive index, we have realized that simultaneous negative or positive lateral shifts are possible for the reflected and transmitted light beams. In our proposed scheme, the lateral shifts at the fixed incident angle are possible only by tuning the optical parameters without needing to change the cavity structure.

Characteristics of an Airy beam at a dielectric interface

A full analytical theory for the reflection and transmission of an Airy beam impinging on a dielectric surface is presented. Based on the plane-wave angular spectrum expansion, the analytical expressions for the reflected and transmitted fields comprising beam modes are derived. To improve the calculation accuracy, the actual beam field retains up to the second-order terms. The influences of decay factor and beam width on the intensity distributions of the incident, reflected, and transmitted beams are studied. In addition, we investigate the effects of decay factor and beam width on the beam shift of the reflected beam near the Brewster angle. There is a giant negative lateral shift near the Brewster angle. Results show that the beam shift decreases and increases with increasing decay factor and beam width, respectively. A comparison with the beam shifts of Airy beams incident on the interface and dielectric slab at the Brewster angle is also discussed. The beam shift of the dielectric slab exists an abrupt increase. Finally, an Airy beam incident from air to the left-handed material (LHM) is considered. Results indicate that the imaging position of the incident Airy beam in the LHM is affected by the incident angle and negative refractive index. Our results may provide some theoretical support for the applications of Airy beams in detection and imaging.

Wave Steering by Relaying Interface States in a Valley-Hall-Derived Photonic Superlattice

Topological notions in physics have become a powerful perspective that leads to the discoveries of topological interface states (TISs). In this work, we present a scheme to achieve negative refraction by leveraging the properties of TISs in a valley photonic crystal (VPC). Due to the chiral characteristics, one type of the TISs deterministically possesses negative dispersion relation, which can cause an obliquely incident wave to undergo a negative lateral shift. By stacking multiple VPC interfaces, the TIS-induced lateral shifts can relay in the transmitted wave towards the far side of incidence. The resultant outgoing wave appears to have undergone negative refraction. This finding is verified in microwave experiments. Our scheme opens new application scenarios for topological systems in bulk wave manipulations.

Electrically controlled lateral shift of the reflected optical beams from a nanocomposite structurally chiral medium

In this paper, we theoretically investigate the influence of an external electric field on the lateral shifts of the reflected right-handed circularly polarized beam from a nanocomposite slab at the edge wavelengths of the photonic bandgaps of the structure. The nanocomposite slab is a non-dissipative dielectric chiral material with the randomly dispersed silver nanoparticles inside it. We show that the increase of the applied electric field results in the decrease of the positive lateral shift at the lower edge of the Bragg gap, while the negative lateral shift at the upper edge of the Bragg gap increases by increasing the applied field. Moreover, we show that the impact of the applied voltage is more noticeable at larger incident angles for both the lower and upper edge wavelengths of the Bragg gap. Also, it is shown that the tilt angle of the chiral structure and the slab thickness have considerable effects on the controlling behavior of the externally applied voltage. Finally, we investigate the effect of the filling fraction of nanoparticles and show that the inclusion of the nanoparticles can change the influence of the applied voltage on the lateral shift of the reflected beams.

Tunable lateral shift of the reflected optical beams from a nanocomposite structurally chiral medium

The lateral shifts of the reflected and transmitted circularly polarized beams from a slab of nanocomposite structurally chiral medium are investigated at the edges of the photonic bandgaps of the structure using the transfer matrix method. The nanocomposite structurally chiral medium consists of the structurally chiral material with the silver nanoparticles randomly dispersed inside it. Due to the presence of metallic nanoparticles, this structure also contains an omnidirectional bandgap in addition to the conventional Bragg gap. By obtaining the co-polarized and cross-polarized reflection and transmission spectra of the structure, we show that only the reflected co-polarized right-handed circularly polarized beam has a considerable lateral shift at the edges of the Bragg gap. Moreover, we have shown that the circularly polarized beams do not have a significant lateral shift at the edges of the nanoparticles created bandgap. We also reveal that the reflected beam experiences a positive lateral shift at the lower edge of the Bragg gap and a negative lateral shift at the upper one. Then we examine the influences of the different parameters, such as the filling fraction of nanoparticles, incidence angle, tilt angle, and slab thickness on the lateral shift of the reflected co-polarized right-handed circularly polarized beam.

The general treatment of giant Goos-Hänchen shift in a slab cavity

In this study, the general treatment to obtain negative/positive giant Goos-Hänchen shifts for a slab cavity is provided. We find that there are two main types of giant shifts: The first type (type I) is associated with near-zero reflection coefficient, and the second type (type II) is associated with extra-large reflection and transmission coefficients. An infinite number of modes for each type are found. The general equations for both types with the model's parameters are presented to exactly locate the modes. Type I appears with near-zero absorption/gaining, while Type II appears with a finite gaining with values depend on the modes. The real values of the modes' susceptibility are found to be almost the same. Both types can generate negative or positive lateral shifts when the susceptibility is slightly modified. We finally present a discussion about their physical explanation and potential applications.

Giant Goos-Hänchen shift in two different enantiomers' chiral molecules via quantum coherence.

The Goos and Hänchen (GH) shifts in reflected and transmitted probe light through a cavity mixture of left- and right-handed chiral molecules into two enantiomer states are investigated. Due to the broken mirror symmetry of the left- and right-handed chiral molecules in the presence of cyclic population transfer, such quantum systems can be selectively excited because of the coexistence of one- and two-photon transitions. With the help of coupling Rabi frequency and damping effects due to scattering processes, the generated GH shifts accompanied by simultaneously negative and positive lateral shifts in reflected and transmitted probe lights are greatly enhanced. It is found that the large negative and positive GH shifts are available in the presence of multiphoton resonance and off-resonance conditions for two different enantiomers' chiral molecules. Moreover, the switching between superluminal and subluminal light propagation is extremely dependent on choosing the left- and right-handed chiral molecules. Furthermore, the effects of pulse shape and mode of Laguerre-Gaussian probe light on the GH shifts that lead to a switch between negative and positive shift are also studied. The negative and positive GH shifts in a reflected and transmitted probe beam for an incident Gaussian and different mode of Laguerre-Gaussian shaped beam with various widths by the use of two different enantiomers' chiral molecules are also discussed.

Theoretical large positive and negative lateral beam shift of the metal cladding waveguide in the mid-infrared region.

A large negative and positive lateral beam shift is presented in the midinfrared region based on the penetration enhancement effect of the ultrahigh order modes in the metal-cladding waveguide. The characteristics of the lateral beam shift have been discussed in theory, and the performance of the ultrahigh order modes is confirmed in an experiment at 5.4µm. The negative and positive lateral shift depends on the derivative of the imaginary part of the propagation constant.

Large tunable negative lateral shift from graphene-based hyperbolic metamaterials backed by a dielectric

Large negative lateral shift from the graphene-based hyperbolic metamaterials (GHMM) backed by a dielectric is theoretically predicted. It is demonstrated that large negative lateral shift for TM polarized reflected beam can be thousands of wavelengths near the Brewster angle. The lateral shift can be tunable by Fermi energy. Numerical simulation results for Gaussian incident beams coincide with the theoretical results from the stationary phase method. The result may have potential application in the design of photoelectronic device and optical communication systems.

Non-reflecting non-magnetic homogeneous polarization splitter and polarization deflector design based on transformation electromagnetics

In this paper, a non-reflecting non-magnetic homogeneous polarization splitter and polarization deflector design method is proposed and investigated. Transformation electromagnetics is used as a powerful tool to achieve a desired functionality. By applying a proper linear transformation and using the fact that for different polarizations, distinct constitutive parameters appear in Maxwell equations, a non-magnetic homogeneous media is obtained that is reflectionless. Anisotropy factor of the designed media is evaluated and a brief discussion of the available tradeoff is given. To test the method, two typical polarization splitter with positive and negative lateral shift are designed. Also, by modifying the proposed polarization splitter and implementing a metallic coating, a polarization deflector is designed. Functionality of design method is validated using commercial finite element software COMSOL Multiphysics. It is seen that the proposed polarization splitters can successfully create desired separation between polarizations according to the design procedure. Also, the polarization deflector can deflect one polarization with respect to the other one by arbitrary angle.

Coherent control of the Goos-Hänchen shift via Fano interference

A scheme of enhanced Goos-Hänchen (GH) shifts in reflected and transmitted light beams is exploited in a cavity, where an asymmetric double AlGaAs/GaAs quantum well structure with resonant tunneling to a common continuum is employed as the intracavity medium. With the help of Fano-type interference induced by resonant tunneling, the generated GH shifts that contain a negative lateral shift in reflected light beam and a positive lateral shift in transmitted light beam are found to be significantly enhanced. More interestingly, these GH shifts in reflected and transmitted light beams are modulated by means of a control beam and external bias voltage, in which maximum negative shift of 1.86 mm and positive shift of 0.37 mm are achievable.

Influence of magnetic surface anisotropy on spin wave reflection from the edge of ferromagnetic film

We study propagation of the Gaussian beam of spin waves and its reflection from the edge of thin yttrium-iron-garnet film with in-plane magnetization perpendicular to this edge. We have performed micromagnetic simulations supported by analytical calculations to investigate the influence of the surface magnetic anisotropy present at the film edge on the reflection, especially in the context of the Goos-H\"anchen effect. We have shown the appearance of a negative lateral shift between reflected and incident spin wave beams' spots. This shift is particularly sensitive to the surface magnetic anisotropy value and is a result of the Goos-H\"anchen shift which is sensitive to the magnitude of the anisotropy and of the bending of the spin wave beam. We have demonstrated that the demagnetizing field provided a graded increase of the refractive index for spin waves, which is responsible for the bending.

Arbitrary positive and negative lateral shift of Gaussian beam reflected from an anisotropic grounded slab

Both positive and negative lateral shifts are demonstrated in this paper for a Gaussian beam reflected from an anisotropic grounded slab, whose constructive parameters are determined by the optical transformation approach. The incident wave is modeled as a tapered wave with a spatial Gaussian shape. Layered structures with alternating isotropic materials are applied to model the parameters of such an anisotropic grounded slab and good agreements are obtained when the positive lateral shifts caused by ideal anisotropic slab are compared with those of the equivalent isotropic layered slab.

Large positive and negative lateral shift in prism-waveguide system with left-handed material of weak absorption

We study the mechanism of large positive and negative lateral shift in a prism-waveguide coupling system where the guiding layer is composed of left-handed material with weak absorption. As the giant lateral shift is always dramatically decreased by the loss of guiding layer, we introduce lossy cladding layer and substrate to realize large lateral shift in the above system, theoretical expression of lateral shift is derived and simulation results illustrate the appearance of large lateral shift.

Negative Goos-Hänchen shift in reflection from subwavelength gratings

A negative Goos–Hanchen (GH) shift of light beam reflecting from planar microphotonic structures consisting of two parallel dielectric subwavelength diffraction gratings is predicted. The phenomenon occurs because the energy flow of the mode guided in the subwavelength structure is predominantly directed in the opposite direction to the energy flow of the incident beam. The numerical calculations show that the negative GH shift can reach approximately six times that of the wavelength in realistic structures, so that the phenomenon can be experimentally observed. In addition to the negative lateral shift, the focusing of the beam in reflection from the grating is also observed as a secondary effect.

Giant negative and positive lateral shifts in graphene superlattices

Electronic analogy of Goos-Hänchen shift has been well established and investigated in various graphene-based nanostructures, including p-n interface, single and double barriers. In this paper, we have studied the giant negative and positive lateral shifts of the transmitted electron beam through graphene superlattices. It is found that the lateral shifts, depending on the location of new Dirac point, can be negative as well as positive near the band edges of zero-k̅ (non-Bragg) gap. We have also achieved the enhanced opposite shifts in the graphene superlattice with defect layer, since such structure possesses the defect mode inside the zero-k̅ gap. The modulations of negative and positive lateral shifts by incidence angles, width and potential height of defect layer may lead to potential applications in the graphene-based electron wave devices.

Surface wave-induced enhancement of the Goos–Hänchen shift in single negative one-dimensional photonic crystal

The Goos–Hänchen (GH) shift in one-dimensional photonic crystal (1DPC), composed of alternate ε-negative and μ-negative materials, is theoretically investigated. It is demonstrated that larger shifts can be obtained when surface modes are excited. It is also found that the magnitude of the lateral GH shift is closely related to intrinsic loss factor. The results show that for a definite value of loss and for values larger than that, backward surface waves which lead to negative lateral GH shifts can be excited. On the other hand, there are large positive GH shifts for small loss factor less than aforementioned definite loss. The GH shift is very sensitive to the thickness of air gap which is necessary to excitation of the surface waves.

Goos-Hänchen shift of self-collimated beam in Kretschmann configuration based on photonic crystal

We perform the finite-difference time-domain (FDTD) simulations and analyze a dual-beam-reflection phenomenon for a Gaussian beam illuminating a Kretschmann configuration composed of a lossless dielectric waveguide between a photonic-crystal-made prism and air. One reflection beam has a small positive shift and the other has a large negative shift in the dual-beam-reflection phenomenon. The FDTD shows that the specific phenomenon takes place just when the corresponding leaky surface mode supported in the Kretschmann configuration is excited. Field profile of the surface mode demonstrates a strong localized stationary field in the dielectric waveguide. We find that the maximum negative lateral shift is -23.23a, corresponding to 4.99 times of the incident wavelength, which is 1.1615 times of the beam waist.

Large negative lateral shifts due to negative refraction

When a thin structure in which negative refraction occurs (a metallo-dielectric structure or a photonic crystal) is illuminated by a beam, the reflected and transmitted beam can undergo a large negative lateral shift. This phenomenon can be seen as an interferential enhancement of the geometrical shift and can be considered a signature of negative refraction.