Showing papers on "Kerr effect published in 2013"
Abstract: The third order nonlinear optical property of Bi2Se3, a kind of topological insulator (TI), has been investigated under femto-second laser excitation. The open and closed aperture Z-scan measurements were used to unambiguously distinguish the real and imaginary part of the third order optical nonlinearity of the TI. When excited at 800 nm, the TI exhibits saturable absorption with a saturation intensity of 10.12 GW/cm2 and a modulation depth of 61.2%, and a giant nonlinear refractive index of 10−14 m2/W, almost six orders of magnitude larger than that of bulk dielectrics. This finding suggests that the TI: Bi2Se3 is indeed a promising nonlinear optical material and thus can find potential applications from passive laser mode locker to optical Kerr effect based photonic devices.
263 citations
TL;DR: The effective interaction between two microwave fields, mediated by a transmon-type superconducting artificial atom which is strongly coupled to a coplanar transmission line, is investigated, producing an effective cross-Kerr coupling.
Abstract: We investigate the effective interaction between two microwave fields, mediated by a transmon-type superconducting artificial atom which is strongly coupled to a coplanar transmission line. The interaction between the fields and atom produces an effective cross-Kerr coupling. We demonstrate average cross-Kerr phase shifts of up to 20 degrees per photon with both coherent microwave fields at the single-photon level. Our results provide an important step toward quantum applications with propagating microwave photons.
201 citations
TL;DR: In this article, patterned electrodes on a piezoelectric substrate are demonstrated to produce a localized strain of sufficient magnitude to control the magnetic anisotropy of a Ni island.
Abstract: Patterned electrodes on a piezoelectric substrate are demonstrated to produce a localized strain of sufficient magnitude to control the magnetic anisotropy of a Ni island. Strain-induced magnetic anisotropy was measured using the magneto-optical Kerr effect, and the measured shifts in magnetic anisotropy were consistent with strain predicted using linear finite element analysis. This approach overcomes the effect of the substrate clamping the in-plane strain and should be scalable to thin films. This approach represents a key step toward realizing the next generation of strain mediated magneto-electric magnetic random access memory devices with low writing energy and high writing speed.
166 citations
TL;DR: It is shown that highly pure 3D magnetic nanowires with aspect-ratios of ~100 can be grown using focused electron-beam-induced-deposition and it is determined that the magnetisation reversal of the wires occurs via the nucleation and propagation of domain walls.
Abstract: Control of the motion of domain walls in magnetic nanowires is at the heart of various recently proposed three-dimensional (3D) memory devices. However, fabricating 3D nanostructures is extremely complicated using standard lithography techniques. Here we show that highly pure 3D magnetic nanowires with aspect-ratios of ~100 can be grown using focused electron-beam-induced-deposition. By combining micromanipulation, Kerr magnetometry and magnetic force microscopy, we determine that the magnetisation reversal of the wires occurs via the nucleation and propagation of domain walls. In addition, we demonstrate that the magnetic switching of individual 3D nanostructures can be directly probed by magneto-optical Kerr effect.
162 citations
TL;DR: In this article, the formation of cavity solitons in crystalline whispering-gallery-mode disk resonators that are pumped in different dispersion regimes is investigated, and the authors use the Lugiato-Lefever spatiotemporal formalism to investigate the temporal dynamics leading to the formation and emergence of these azimuthal solitions, as well as the emergence of Turing patterns.
Abstract: We investigate the formation of cavity solitons in crystalline whispering-gallery-mode disk resonators that are pumped in different dispersion regimes. In the Fourier domain, these dissipative structures correspond to specific types of mode-locked Kerr optical frequency combs. Depending on the sign of the second-order chromatic dispersion and on the pumping conditions, we show that either bright or dark cavity solitons can emerge, and we show that these two regimes are associated with characteristic spectral signatures that can be discriminated experimentally. We use the Lugiato-Lefever spatiotemporal formalism to investigate the temporal dynamics leading to the formation of these azimuthal solitons, as well as the emergence of Turing patterns. The theoretical results are in excellent agreement with experimental measurements that are obtained using calcium and magnesium fluoride disk resonators pumped near 1550 nm.
152 citations
TL;DR: Theoretical simulations indicate that the physical mechanism of SC generation is due to nonlinear effects in fibers, and the cascaded Raman scattering is responsible for significant spectral broadening in the longer wavelength regions whereas the Kerr effect results in smoothing of SC generated spectrum.
Abstract: We report generation of broadband supercontinuum (SC) by noise-like pulses (NLPs) with a central wavelength of 1070 nm propagating through a long piece of standard single-mode fibers (~100 meters) in normal dispersion region far from the zero-dispersion point. Theoretical simulations indicate that the physical mechanism of SC generation is due to nonlinear effects in fibers. The cascaded Raman scattering is responsible for significant spectral broadening in the longer wavelength regions whereas the Kerr effect results in smoothing of SC generated spectrum. The SC exhibits low threshold (43 nJ) and a flat spectrum over 1050-1250 nm.
134 citations
TL;DR: The present results may facilitate the design and fabrication of new magnetic alloys with large perpendicular magnetic anisotropy and tailored damping properties.
Abstract: The dependence of the intrinsic Gilbert damping parameter α(0) on the spin-orbital coupling strength ξ is investigated in L1(0) ordered FePd(1-x) Pt(x) films by time-resolved magneto-optical Kerr effect measurements and spin-dependent ab initio calculations. Continuous tuning of α(0) over more than one order of magnitude is realized by changing the Pt/Pd concentration ratio showing that α(0) is proportional to ξ(2) as changes of other leading parameters are found to be negligible. The perpendicular magnetic anisotropy is shown to have a similar variation trend with x. The present results may facilitate the design and fabrication of new magnetic alloys with large perpendicular magnetic anisotropy and tailored damping properties.
132 citations
TL;DR: A simple and robust structure for realizing asymmetric Fano transmission characteristics in photonic crystal waveguide-cavity structures is presented and a significant energy reduction by employing Fano resonances compared to more well established Lorentzian resonance structures is suggested.
Abstract: We present a simple and robust structure for realizing asymmetric Fano transmission characteristics in photonic crystal waveguide-cavity structures. The use of Fano resonances for optical switching is analyzed using temporal coupled mode theory in combination with three-dimensional finite difference time domain simulations taking into account the signal bandwidth. The results suggest a significant energy reduction by employing Fano resonances compared to more well established Lorentzian resonance structures. A specific example of a Kerr nonlinearity shows an order of magnitude energy reduction.
110 citations
TL;DR: It is proved that only the spin-orbit induced transverse plasmon plays an active role on the magneto-optical properties by controlling the relative amplitude and phase lag between the two oscillators.
Abstract: We explore the influence of the phase of localized plasmon resonances on the magneto-optical activity of nanoferromagnets. We demonstrate that these systems can be described as two orthogonal damped oscillators coupled by the spin-orbit interaction. We prove that only the spin-orbit induced transverse plasmon plays an active role on the magneto-optical properties by controlling the relative amplitude and phase lag between the two oscillators. Our theoretical predictions are fully confirmed by magneto-optical Kerr effect and optical extinction measurements in nanostructures of different size and shape.
110 citations
TL;DR: In this paper, a hybrid structure of a magneto-optical photonic waveguide with plasmonic (gold) nanowires was demonstrated to significantly boost an important effect, the so-called transverse magnetooptical Kerr effect.
Abstract: Properties of light propagating in some materials can be influenced by a static magnetic field. Such magneto-optical effects are useful, but their strength is limited traditionally by the materials used. Scientists demonstrate that a hybrid structure of a magneto-optical photonic waveguide with plasmonic (gold) nanowires significantly boosts an important effect, the so-called transverse magneto-optical Kerr effect, through resonant interaction between the waveguide photons and the plasmons.
107 citations
TL;DR: In this article, the spectral properties of the transverse magneto-optical Kerr effect in periodic metal-dielectric hybrid structures are studied, in particular with respect to the achievable magnitude.
Abstract: The spectral properties of the transverse magneto-optical Kerr effect (TMOKE) in periodic metal-dielectric hybrid structures are studied, in particular with respect to the achievable magnitude. It is shown that the TMOKE is sensitive to the magneto-optical activity of the bismuth-substituted rare-earth iron garnet, which is used as a dielectric material in the investigated structures. For samples with larger Bi substitution level and, consequently, larger gyration
TL;DR: In this paper, the photonic spin Hall effect (SHE) of a Gaussian beam reflected from the interface between air and topological insulators (TIs) is attributed to spin-orbit coupling and manifests itself as in-plane and transverse spin-dependent splitting.
Abstract: In this paper we theoretically investigate the photonic spin Hall effect (SHE) of a Gaussian beam reflected from the interface between air and topological insulators (TIs). The photonic SHE is attributed to spin-orbit coupling and manifests itself as in-plane and transverse spin-dependent splitting. We reveal that the spin-orbit coupling effect in TIs can be routed by adjusting the axion angle variations. We find that, unlike the transverse spin-dependent splitting, the in-plane one is sensitive to the axion angle. It is shown that the polarization structure in the magneto-optical Kerr effect is significantly altered due to the spin-dependent splitting in the photonic SHE. We theoretically propose a weak measurement method to determine the strength of axion coupling by probing the in-plane splitting of the photonic SHE.
TL;DR: In this article, the interaction between a Λ-type three-level atom and a two-mode cavity field is discussed, where the detuning parameters and cross-Kerr nonlinearity are taken into account, and it is assumed that the atom-field coupling and Kerr medium are f-deformed.
Abstract: In this paper, the interaction between a Λ-type three-level atom and a two-mode cavity field is discussed. The detuning parameters and cross-Kerr nonlinearity are taken into account, and it is assumed that the atom–field coupling and Kerr medium are f-deformed. Even though the system seems complicated, the analytical form of the state vector of the entire system for the considered model is exactly obtained. The time evolution of nonclassical properties, such as quantum entanglement and position–momentum entropic uncertainty relation (entropy squeezing) of the field are investigated. In each case, the influences of the detuning parameters, generalized Kerr medium, and intensity-dependent coupling on the latter nonclassicality signs are analyzed in detail.
TL;DR: In this article, the influence of a nanoscale periodic ripple morphology on the structure and magnetocrystalline anisotropy of thin ferromagnetic (FM) Ni, Co, and Fe films was investigated.
Abstract: We investigate the influence of a nanoscale periodic ripple morphology on the structure and magnetocrystalline anisotropy of thin ferromagnetic (FM) Ni${}_{81}$Fe${}_{19}$, Co, and Fe films. The ripples are created by ion beam erosion of the Si substrate. The periodic ripple structures induce a uniaxial magnetic anisotropy (UMA) in the FM films as confirmed by ferromagnetic resonance and magneto-optical Kerr effect measurements. The thickness dependence of the UMA reveals an abrupt transition. For a thin film regime there is a corrugated alignment of the magnetic moments and above a critical thickness one has dipolar interactions due to the sinusoidal surface modulations.
TL;DR: In this paper, the authors studied the Gilbert damping in perpendicularly magnetized Pt/Co/AlOx films by means of the time-resolved magneto-optical Kerr effect.
Abstract: The Gilbert damping in perpendicularly magnetized Pt/Co/AlOx films is studied by means of the time-resolved magneto-optical Kerr effect. The Gilbert damping constant is observed to depend strongly on the AlOx layer thickness and the applied magnetic field. The magnetic field dependence is explained by extrinsic contributions to the damping due to inhomogeinities in the thin films. The intrinsic Gilbert damping is found to vary between 0.11 and 0.28 as a function of the AlOx thickness, which can be attributed to spin pumping from Co into the adjacent Pt film.
TL;DR: The key theoretical result is that the principal refractive indices of homogenized VADHFLC cells exhibit the quadratic nonlinearity and such behavior might be interpreted as an orientational Kerr effect caused by the electric-field-induced orientational distortions of the FLC helix.
Abstract: We study both theoretically and experimentally the electro-optical properties of vertically aligned deformed helix ferroelectric liquid crystals (VADHFLC) with subwavelength pitch that are governed by the electrically induced optical biaxiality of the smectic helical structure. The key theoretical result is that the principal refractive indices of homogenized VADHFLC cells exhibit the quadratic nonlinearity and such behavior might be interpreted as an orientational Kerr effect caused by the electric-field-induced orientational distortions of the FLC helix. In our experiments, it has been observed that, for sufficiently weak electric fields, the magnitude of biaxiality is proportional to the square of electric field in good agreement with our theoretical results for the effective dielectric tensor of VADHFLCs. Under certain conditions, the 2$\ensuremath{\pi}$ phase modulation of light, which is caused by one of the induced refractive indices, is observed without changes in ellipticity of incident light.
TL;DR: In this paper, the atomic nonlinear polarization induced by high-intensity ultrashort laser pulses in hydrogen was modeled by numerically solving the time-dependent Schrodinger equation.
Abstract: Motivated by the ongoing controversy over the origin of the nonlinear index saturation and subsequent intensity clamping in femtosecond filaments, we study the atomic nonlinear polarization induced by high-intensity ultrashort laser pulses in hydrogen by numerically solving the time-dependent Schr\"odinger equation. Special emphasis is given to the efficient modeling of the nonlinear polarization at a central laser frequency corresponding to a wavelength of 800 nm. Here, the recently proposed model of the higher-order Kerr effect (HOKE) and two versions of the standard model for femtosecond filamentation, including either a multiphoton or tunnel ionization rate, are compared. We find that around the clamping intensity the instantaneous HOKE model does not reproduce the temporal structure of the nonlinear response obtained from the quantum-mechanical results. In contrast, the noninstantaneous charge contributions included in the standard models ensure a reasonable quantitative agreement. Therefore, the physical origin for the observed saturation of the overall electron response is confirmed to mainly result from contributions of free or nearly-free electrons.
TL;DR: In this article, a generalized model for the intensity-dependent response of atoms in strong IR laser fields, describing deviations in the nonlinear response at the frequency of the driving field from the standard model, is presented.
Abstract: We discuss the connection between strong-field ionization, saturation of the Kerr response and the formation of the Kramers?Henneberger (KH) atom and long-living excitations in intense infrared (IR) external fields. We present a generalized model for the intensity-dependent response of atoms in strong IR laser fields, describing deviations in the nonlinear response at the frequency of the driving field from the standard model. We show that shaping the driving laser pulse allows one to reveal signatures of the excited KH states in the Kerr response of an individual atom.
TL;DR: In this article, the terahertz-induced third-order nonlinear optical properties of amorphous chalcogenide glasses As2S3 and As2Se3 were investigated.
Abstract: We have investigated the terahertz-induced third-order (Kerr) nonlinear optical properties of the amorphous chalcogenide glasses As2S3 and As2Se3. Chalcogenide glasses are known for their high optical Kerr nonlinearities which can be several hundred times greater than those of fused silica. We use high-intensity, single-cycle terahertz pulses with a maximum electrical field strength exceeding 400 kV/cm and frequency content from 0.2 to 3.0 THz. By optical Kerr-gate sampling, we measured the terahertz-induced nonlinear refractive indices at 800 nm to be n2=1.746×10−14cm2/W for As2S3 and n2=3.440×10−14 cm2/W for As2Se3.
TL;DR: It is demonstrated that by hybridization of surface and cavity resonances in this 1D plasmonic grating, the transverse Kerr effect can be further enhanced, extinguished or even switched in sign and that without inverting or modifying the film's magnetization.
Abstract: We show that the enhancement of the transverse magneto-optical Kerr effect of a smooth magnetic dielectric film covered by a noble metal grating, is strongly dependent on the precise geometry of this grating. Up till now this magnetoplasmonic enhancement was solely attributed to a nonreciprocal shift of the dispersion of the surface plasmon polariton resonances at the interface with the magnetized substrate. It is demonstrated that by hybridization of surface and cavity resonances in this 1D plasmonic grating, the transverse Kerr effect can be further enhanced, extinguished or even switched in sign and that without inverting or modifying the film’s magnetization. This strong geometrical dispersion and the accompanying anomalous sign change of the magneto-plasmonic effects in such systems has never been considered before, and might find interesting applications in sensing and nanophotonics.
TL;DR: A refraction model is developed that optimized the parameters affecting the electro-optics of IPS-BPLC, such as electrode dimension, saturated induced birefringence, saturation electric field, and cell gap, to achieve low operation voltage and high transmittance with single gamma curve.
Abstract: We develop a refraction model to analyze the electro-optic effects of an in-plane-switching blue phase liquid crystal (IPS-BPLC) cell. Good agreement with experiment is obtained. Based on this model, we optimize the parameters affecting the electro-optics of IPS-BPLC, such as electrode dimension, saturated induced birefringence, saturation electric field, and cell gap. An IPS-BPLC with low operation voltage (<10V(rms)) and high transmittance (~80%) with single gamma curve can be achieved by optimizing the BPLC material and device structure.
TL;DR: In this paper, the dipole and quadrupole plasmon resonances of Au triangular nanoprisms were investigated experimentally and theoretically, and it was shown that large electric fields are confined at the tips of the Au prisms, leading to large third-order optical nonlinearities.
Abstract: Au triangular nanoprisms have been prepared by the wet chemical method. By using absorption measurements and finite difference time domain (FDTD) calculations, the dipole and quadrupole plasmon resonances of Au triangular nanoprisms are investigated experimentally and theoretically. Calculations show that large electric fields are confined at the tips of the Au prisms, leading to large third-order optical nonlinearities. The Z-scan measurements show a third-order optical susceptibility of about 1.25 × 10–11 esu at 1240 nm, which is 19 times larger than that at 800 nm. The ultrafast light response time is about 482 fs measured by optical Kerr effect technique at 800 nm. The distinct third-order optical nonlinearities and the ultrafast response time enable the Au triangular prisms to be a good candidate for future all-optical switches and ultrafast optical information manipulators.
TL;DR: In this paper, it was shown that the striking Kerr onset seen in the pseudogap phase of a large number of cuprate high temperature superconductors is evidence of chiral charge ordering.
Abstract: The Kerr effect can arise in a time-reversal invariant dissipative medium that is "gyrotropic", i.e. one that breaks inversion ($\mathcal I$) and all mirror symmetries. Examples of such systems include electron analogs of cholesteric liquid crystals, and their descendants, such as systems with chiral charge ordering. We present arguments that the striking Kerr onset seen in the pseudogap phase of a large number of cuprate high temperature superconductors is evidence of chiral charge ordering. We discuss additional experimental consequences of a phase transition to a gyrotropic state, including the appearance of a zero field Nernst effect.
TL;DR: Analytical considerations of "self-mode-locked" operation in a typical vertical external-cavity surface-emitting laser (VECSEL) cavity geometry by means of Kerr lens action in the semiconductor gain chip are presented.
Abstract: We present analytical considerations of "self-mode-locked" operation in a typical vertical external-cavity surface-emitting laser (VECSEL) cavity geometry by means of Kerr lens action in the semiconductor gain chip. We predict Kerr-lens mode-locked operation for both soft- and hard-apertures placed at the optimal intra-cavity positions. These predictions are experimentally verified in a Kerr-lens mode-locked VECSEL capable of producing pulse durations of below 500 fs at 1 GHz repetition rate.
TL;DR: In this article, the authors describe an experimental study performed on multilayered, permalloy-based thin films deposited by sputtering under a magnetic field that produces a homogeneous uniaxial anisotropy in the plane of the film.
Abstract: The sensitivity of magnetic sensors based on the Giant Magneto-Impedance effect can be enhanced using high permeability materials with a well-defined but small transverse anisotropy. We describe an experimental study performed on multilayered, permalloy-based thin films deposited by sputtering under a magnetic field that produces a homogeneous uniaxial anisotropy in the plane of the film. Patterning of the deposit by photolithographic methods into strip-shaped samples (with their long direction perpendicular to the induced anisotropy) establishes a longitudinal shape anisotropy that competes with the transversal one induced at deposition. The combination and competition of the two mutually perpendicular uniaxial anisotropies result in an effective one with a reduced magnitude (the difference between both of them) in the transversal direction. As the strength of the shape anisotropy is determined by the relation between width and length of the stripe, the magnitude of the effective anisotropy can be conveniently modulated by adequately selecting the aspect ratio of the patterned sample. The hysteresis loops measured by Kerr effect magnetometry confirm that the effective transversal anisotropy field can be reduced from 5 to 1 Oe which should concomitantly increase the sensitivity of thin film magneto-impedance sensors.
TL;DR: In this paper, the authors demonstrate that in order to achieve self-focusing in a hyperbolic wire medium, a nonlinear self-defocusing Kerr medium must be used as a dielectric host.
Abstract: Subwavelength confinement of light in nonlinear hyperbolic metamaterials due to formation of spatial solitons has attracted much recent attention because of its seemingly counterintuitive behavior. In order to achieve self-focusing in a hyperbolic wire medium, a nonlinear self-defocusing Kerr medium must be used as a dielectric host. Here we demonstrate that this behavior finds a natural explanation in terms of the analog of gravity. A wave equation describing the propagation of extraordinary light inside hyperbolic metamaterials exhibits (2+1)-dimensional Lorentz symmetry. The role of time in the corresponding effective three-dimensional Minkowski space-time is played by the spatial coordinate aligned with the optical axis of the metamaterial. Nonlinear optical Kerr effect ``bends'' this space-time resulting in effective gravitational force between extraordinary photons. In order for the effective gravitational constant to be positive, a negative self-defocusing Kerr medium must be used as a host. If gravitational self-interaction is strong enough, the spatial soliton may collapse into a black hole analog.
TL;DR: EO observations show that the BPII produced exhibited stable EO performance based on the EO Kerr effect, and this material demonstrated very fast, sub-millisecond-scale, response times, thus showing potential for use in high-speed EO devices.
Abstract: A thermodynamically stable blue phase II (BPII) has been prepared, and its electrooptical (EO) performance has been evaluated in a host system of a conventional rodlike nematogen mixed with a bent-core molecule. For the mixed system presented, the widest temperature range of BPII stability, during cooling/heating, was >6 °C. This range is much wider than those of conventional nematogens blended with chiral dopants. EO observations show that the BPII produced exhibited stable EO performance based on the EO Kerr effect. The temperature dependence of the Kerr effect was found to be in approximate agreement with the Landau-de Gennes theory. Furthermore, this material demonstrated very fast, sub-millisecond-scale, response times, thus showing potential for use in high-speed EO devices.
TL;DR: In this article, the magnetic and Gilbert damping properties of Co2FeAl film with L21 structure were studied by ferromagnetic resonance (FMR) and time-resolved magneto-optical Kerr effect (TR-MOKE), respectively.
Abstract: Co2FeAl film with L21 structure was prepared. Its magnetic and Gilbert damping properties were studied by ferromagnetic resonance (FMR) and time-resolved magneto-optical Kerr effect (TR-MOKE), respectively. It is observed that the apparent damping parameter decreases drastically with increasing magnetic field at low field regime and eventually becomes a constant value of 0.004 at high field regime by TR-MOKE measurements. A Gilbert damping parameter of 0.008 in the hard axis by FMR measurement has also been obtained, which is comparable with that extracted from TR-MOKE measurements at low external field, indicating the extrinsic damping processes involved in the low field regime.
TL;DR: In this article, an ultrafast and low-power all-optical tunable plasmon-induced transparency in a polycrystalline lithium niobate layer was achieved based on strong quantum confinement enhancing nonlinearity.
Abstract: We report an ultrafast and low-power all-optical tunable plasmon-induced transparency in a plasmonic nanostructure consisting of a gold nanowire grating embedded in a polycrystalline lithium niobate layer, realized based on strong quantum confinement enhancing nonlinearity. The all-optical tunability is realized based on the third-order nonlinear Kerr effect. A shift of 30 nm in the central wavelength of the transparency window is achieved under excitation of a pump light with an intensity as low as 7 MW/cm2. An ultrafast response time of 69 ps is reached because of ultrafast relaxation dynamics of bound electrons in polycrystalline lithium niobate.
TL;DR: This work repeatedly and reproducibly switched a GaAs-AlAs planar microcavity operating in the " original" telecom band by exploiting the virtually instantaneous electronic Kerr effect, and achieves repetition times as fast as 300 fs, thereby breaking the terahertz modulation barrier.
Abstract: We have repeatedly and reproducibly switched a GaAs-AlAs planar microcavity operating in the “original” telecom band by exploiting the virtually instantaneous electronic Kerr effect. We achieve repetition times as fast as 300 fs, thereby breaking the terahertz modulation barrier. The rate of the switching in our experiments is only determined by optics and not by material-related relaxation. Our results offer opportunities for fundamental studies of cavity quantum electrodynamics and optical information processing in the subpicosecond time scale.