Showing papers on "Kerr effect published in 2017"
TL;DR: In this article, the authors show that the Kerr effect in a graded-index (GRIN) MMF is the driving mechanism that overcomes speckle distortions, and leads to a counterintuitive effect that results in a spatially clean output beam robust against fibre bending.
Abstract: The Kerr effect in graded-index multimode fibres drives a spatial beam self-cleaning phenomenon that withstands fibre bending and does not necessitate dissipative processes such as stimulated scattering. Multimode optical fibres are enjoying renewed attention, boosted by the urgent need to overcome the current capacity crunch of single-mode fibre (SMF) systems and by recent advances in multimode complex nonlinear optics1,2,3,4,5,6,7,8,9,10,11,12,13. In this work, we demonstrate that standard multimode fibres (MMFs) can be used as ultrafast all-optical tools for the transverse beam manipulation of high-power laser pulses. Our experimental data show that the Kerr effect in a graded-index (GRIN) MMF is the driving mechanism that overcomes speckle distortions, and leads to a counterintuitive effect that results in a spatially clean output beam robust against fibre bending. Our observations demonstrate that nonlinear beam reshaping into the fundamental mode of a MMF can be achieved even in the absence of a dissipative process such as stimulated scattering (Raman or Brillouin)14,15.
390 citations
TL;DR: In this paper, direct-current fields across p-i-n junctions in silicon ridge waveguides were applied to perturb the permittivity of the direct-c. Kerr effect and achieve phase-only modulation and second-harmonic generation.
Abstract: The symmetry of crystalline silicon inhibits a second-order optical nonlinear susceptibility, χ(2), in complementary metal–oxide–semiconductor-compatible silicon photonic platforms. However, χ(2) is required for important processes such as phase-only modulation, second-harmonic generation (SHG) and sum/difference frequency generation. Here, we break the crystalline symmetry by applying direct-current fields across p–i–n junctions in silicon ridge waveguides and induce a χ(2) proportional to the large χ(3) of silicon. The obtained χ(2) is first used to perturb the permittivity (the direct-current Kerr effect) and achieve phase-only modulation. Second, the spatial distribution of χ(2) is altered by periodically patterning p–i–n junctions to quasi-phase-match pump and second-harmonic modes and realize SHG. We measure a maximum SHG efficiency of P2ω/Pω2 = 13 ± 0.5% W−1 at λω = 2.29 µm and with field-induced χ(2) = 41 ± 1.5 pm V–1. We expect such field-induced χ(2) in silicon to lead to a new class of complex integrated devices such as carrier-envelope offset frequency stabilizers, terahertz generators, optical parametric oscillators and chirp-free modulators. The application of d.c. fields across p–i–n junctions in silicon ridge waveguides leads to crystal symmetry breaking. This induces a second-order optical nonlinear susceptibility that enables phase-only modulation and second-harmonic generation with an efficiency of ∼13% W–1 at 2.29 µm.
229 citations
22 Sep 2017
TL;DR: In this article, a microwave photonic intensity differentiator based on a Kerr optical comb generated by a compact integrated micro-ring resonator (MRR) is proposed and experimentally demonstrated.
Abstract: We propose and experimentally demonstrate a microwave photonic intensity differentiator based on a Kerr optical comb generated by a compact integrated micro-ring resonator (MRR). The on-chip Kerr optical comb, containing a large number of comb lines, serves as a high-performance multi-wavelength source for implementing a transversal filter, which will greatly reduce the cost, size, and complexity of the system. Moreover, owing to the compactness of the integrated MRR, frequency spacings of up to 200-GHz can be achieved, enabling a potential operation bandwidth of over 100 GHz. By programming and shaping individual comb lines according to calculated tap weights, a reconfigurable intensity differentiator with variable differentiation orders can be realized. The operation principle is theoretically analyzed, and experimental demonstrations of the first-, second-, and third-order differentiation functions based on this principle are presented. The radio frequency amplitude and phase responses of multi-order intensity differentiations are characterized, and system demonstrations of real-time differentiations for a Gaussian input signal are also performed. The experimental results show good agreement with theory, confirming the effectiveness of our approach.
157 citations
TL;DR: In this paper, the exact bright and singular optical solitons of the nonlinear Schrodinger equation with third and fourth order dispersion terms were presented, and the method of undetermined coefficients was applied to obtain the reported solutions.
127 citations
TL;DR: In this article, the magnetization reversals of exchange-coupled and exchange-decoupled Nd-Fe-B sintered magnets with coercivities of 1.16 and 1.80 T, respectively, were observed by magneto-optical Kerr effect (MOKE) microscopy.
93 citations
20 Aug 2017
TL;DR: In this paper, the authors provide theoretical and experimental evidence for a universal mechanism through which temporal cavity solitons (CSs) can form robust long-range bound states, where the perturbation excites a narrowband resonance in the soliton spectrum, giving long oscillatory tails to the CSs.
Abstract: Temporal cavity solitons (CSs) are pulses of light that can persist in coherently driven passive resonators, such as fiber ring resonators and monolithic Kerr microresonators. While these solitons can in principle occupy arbitrary positions, multisoliton configurations often appear rigidly frozen in time, seemingly insensitive to noise. Here, we elucidate this behavior by presenting theoretical and experimental evidence of a universal mechanism through which temporal CSs can form robust long-range bound states. These bound states require perturbations to the strict Lugiato–Lefever mean-field description of temporal CSs. Binding occurs when the perturbation excites a narrowband resonance in the soliton spectrum, which gives long oscillatory tails to the CSs. Those tails can then interlock for a discrete set of temporal separations between the solitons. The universality of this mechanism is demonstrated in fiber ring cavities by providing experimental observations of long-range bound states ensuing from three different perturbations: third-order dispersion (dispersive wave generation), the periodic nature of the cavity (Kelly sidebands), and the random birefringence of the resonator. Subpicosecond resolution of bound-state separations and their dynamics are obtained by using the dispersive Fourier transform technique. Good agreement with theoretical models, including a new vector mean-field model, is also reported. Our work provides a framework to better understand the many soliton bound states observed in externally driven, passive Kerr resonators, including the soliton crystals reported in microresonators.
81 citations
TL;DR: It is experimentally demonstrate that Kerr spatial self-cleaning of a pulsed beam can be obtained in an amplifying multimode optical fiber and compares the self- Cleaning behavior observed in the same fiber with loss and with gain.
Abstract: We experimentally demonstrate that Kerr spatial self-cleaning of a pulsed beam can be obtained in an amplifying multimode optical fiber. An input peak power of 500 W only was sufficient to produce a quasi-single-mode emission from the double-clad ytterbium doped multimode fiber (YMMF) with non-parabolic refractive index profile. We compare the self-cleaning behavior observed in the same fiber with loss and with gain. Laser gain introduces new opportunities to achieve spatial self-cleaning of light in multimode fibers at a relatively low power threshold.
72 citations
TL;DR: Experimental observation of dispersive waves generated by an additional transient anomalous dispersion from gas ionization in the mid-infrared embedded in a 4.7-octave-wide supercontinuum that uniquely reaches simultaneously to the vacuum ultraviolet, with up to 1.7 W of total average power.
Abstract: Gas-filled hollow-core photonic crystal fibre is being used to generate ever wider supercontinuum spectra, in particular via dispersive wave emission in the deep and vacuum ultraviolet, with a multitude of applications. Dispersive waves are the result of nonlinear transfer of energy from a self-compressed soliton, a process that relies crucially on phase-matching. It was recently predicted that, in the strong-field regime, the additional transient anomalous dispersion introduced by gas ionization would allow phase-matched dispersive wave generation in the mid-infrared—something that is forbidden in the absence of free electrons. Here we report the experimental observation of such mid-infrared dispersive waves, embedded in a 4.7-octave-wide supercontinuum that uniquely reaches simultaneously to the vacuum ultraviolet, with up to 1.7 W of total average power. Dispersive wave emission in gas-filled hollow-core photonic crystal fibres has been possible in the visible and ultraviolet via the optical Kerr effect. Here, Kottig et al. demonstrate dispersive waves generated by an additional transient anomalous dispersion from gas ionization in the mid-infrared.
57 citations
TL;DR: It is shown theoretically that a strong, narrowband Raman gain determines a maximum microresonator size allowable to achieve comb formation and experimentally there exists a competition between Raman and Kerr effects that leads to the existence of two different comb states.
Abstract: We investigate the effects of Raman and Kerr gain in crystalline microresonators and determine the conditions required to generate mode-locked frequency combs. We show theoretically that a strong, narrowband Raman gain determines a maximum microresonator size allowable to achieve comb formation. We verify this condition experimentally in diamond and silicon microresonators and show that there exists a competition between Raman and Kerr effects that leads to the existence of two different comb states.
56 citations
TL;DR: It is demonstrated that Hopf bifurcations can be efficiently controlled with a low energy signal via four-wave mixing and provided new understanding of the effect of coherent wave mixing in the thermal stability regions of optical micro-cavities, fundamental for micro-resonator-based applications in communications, sensing, and metrology.
Abstract: We propose a scheme for bifurcation control in micro-cavities based on the interplay between the ultrafast Kerr effect and a slow nonlinearity, such as thermo-optical, free-carriers-induced, or opto-mechanical one. We demonstrate that Hopf bifurcations can be efficiently controlled with a low energy signal via four-wave mixing. Our results show that new strategies are possible for designing efficient micro-cavity-based oscillators and sensors. Moreover, they provide new understanding of the effect of coherent wave mixing in the thermal stability regions of optical micro-cavities, fundamental for micro-resonator-based applications in communications, sensing, and metrology, including optical micro-combs.
55 citations
08 Nov 2017
TL;DR: A highly sensitive sensor based on enhancing the transversal magneto-optical Kerr effect (TMOKE) through excitation of surface plasmon resonances in a novel and simple architecture, which consists of a metal grating on a metal magneto -optical layer.
Abstract: We propose a highly sensitive sensor based on enhancing the transversal magneto-optical Kerr effect (TMOKE) through excitation of surface plasmon resonances in a novel and simple architecture, which consists of a metal grating on a metal magneto-optical layer. Detection of the change in the refractive index of the analyte medium is made by monitoring the angular shift of the Fano-like resonances associated with TMOKE. A higher resolution is obtained with this technique than with reflectance curves. The key aspect of the novel architecture is to achieve excitation of surface plasmon resonances mainly localized at the sensing layer, where interaction with the analyte occurs. This led to a high sensitivity, S = 190° RIU–1, and high performance with a figure of merit of the order of 103, which can be exploited in sensors and biosensors.
TL;DR: This holistic empirical study provides relevant guidelines to optimize the properties of LPCVD silicon nitride waveguides for nonlinear optics applications that rely on the Kerr effect.
Abstract: Silicon nitride is awell-established material for photonic devices and integrated circuits. It displays a broad transparency window spanning from the visible to the mid-IR and waveguides can be manufactured with low losses. An absence of nonlinear multi-photon absorption in the erbium lightwave communications band has enabled various nonlinear optic applications in the past decade. Silicon nitride is a dielectric material whose optical and mechanical properties strongly depend on the deposition conditions. In particular, the optical bandgap can be modified with the gas flow ratio during low-pressure chemical vapor deposition (LPCVD). Here we show that this parameter can be controlled in a highly reproducible manner, providing an approach to synthesize the nonlinear Kerr coefficient of the material. This holistic empirical study provides relevant guidelines to optimize the properties of LPCVD silicon nitride waveguides for nonlinear optics applications that rely on the Kerr effect.
20 Mar 2017
TL;DR: The constituent cores of multi-core fibers are coupled by acoustic modes, guided by the entire cladding cross-section, which leads to inter core cross phase modulation.
Abstract: Optical fibers containing multiple cores are widely regarded as the leading solution to the optical communications capacity crunch. The most prevalent paradigm for the design and employment of multi-core fibers relies on the suppression of direct coupling of optical power among cores. The cores, however, remain mechanically coupled. Inter-core, opto-mechanical cross-talk, among cores that are otherwise optically isolated from one another, is shown in this work for the first time, to the best of our knowledge. Light in one core stimulates guided acoustic modes of the entire fiber cladding. These modes, in turn, induce refractive index perturbations that extend across to other cores. Unlike corresponding processes in standard fiber, light waves in off-axis cores stimulate general torsional–radial guided acoustic modes of the cylindrical cross section. Hundreds of such modes give rise to inter-core cross-phase modulation, with broad spectra that are quasi-continuous up to 1 GHz frequency. Inter-core cross-talk in a commercial, seven-core fiber is studied in both analysis and experiment. Opto-mechanical cross-talk is quantified in terms of an equivalent nonlinear coefficient, per acoustic mode or per frequency. The nonlinear coefficient may reach 1.9[W×km]−1, a value that is comparable with that of the intra-core Kerr effect in the same fiber.
Journal Article•
TL;DR: It is shown that for layered collinear antiferromagnets, magneto-optic effects can be generated and manipulated by controlling crystal symmetries through a gate voltage, and the field-induced inversion symmetry breaking effect leads to gate-controllable MOKE, whose direction of rotation can be switched by the reversal of the gate voltage.
Abstract: Using symmetry arguments and a tight-binding model, we show that for layered collinear antiferromagnets, magneto-optic effects can be generated and manipulated by controlling crystal symmetries through a gate voltage. This provides a promising route for electric field manipulation of the magneto-optic effects without modifying the underlying magnetic structure. We further demonstrate the gate control of the magneto-optic Kerr effect (MOKE) in bilayer MnPSe_{3} using first-principles calculations. The field-induced inversion symmetry breaking effect leads to gate-controllable MOKE, whose direction of rotation can be switched by the reversal of the gate voltage.
Journal Article•
TL;DR: In this article, the femtosecond magneto-optical Kerr effect was used to excite and probe the magnetization dynamics in two thin-film ferromagnets with different lattice structures: crystalline Fe and amorphous CoFeB.
Abstract: We use single-cycle THz fields and the femtosecond magneto-optical Kerr effect to, respectively, excite and probe the magnetization dynamics in two thin-film ferromagnets with different lattice structures: crystalline Fe and amorphous CoFeB We observe Landau-Lifshitz-torque magnetization dynamics of comparable magnitude in both systems, but only the amorphous sample shows ultrafast demagnetization caused by the spin-lattice depolarization of the THz-induced ultrafast spin current Quantitative modeling shows that such spin-lattice scattering events occur on similar time scales than the conventional spin conserving electronic scattering (∼30 fs) This is significantly faster than optical laser-induced demagnetization THz conductivity measurements point towards the influence of lattice disorder in amorphous CoFeB as the driving force for enhanced spin-lattice scattering
TL;DR: In this paper, the optical bandgap can be modified with the gas flow ratio during low-pressure chemical vapor deposition (LPCVD) in order to synthesize the nonlinear Kerr coefficient of the material.
Abstract: Silicon nitride is a well-established material for photonic devices and integrated circuits. It displays a broad transparency window spanning from the visible to the mid-IR and waveguides can be manufactured with low losses. An absence of nonlinear multi-photon absorption in the erbium lightwave communications band has enabled various nonlinear optic applications in the past decade. Silicon nitride is a dielectric material whose optical and mechanical properties strongly depend on the deposition conditions. In particular, the optical bandgap can be modified with the gas flow ratio during low-pressure chemical vapor deposition (LPCVD). Here we show that this parameter can be controlled in a highly reproducible manner, providing an approach to synthesize the nonlinear Kerr coefficient of the material. This holistic empirical study provides relevant guidelines to optimize the properties of LPCVD silicon nitride waveguides for nonlinear optics applications that rely on the Kerr effect.
TL;DR: In this paper, the authors have observed period-tripling subharmonic oscillations in a driven superconducting coplanar waveguide resonator operated in the quantum regime, kappa T-B << hw.
Abstract: We have observed period-tripling subharmonic oscillations in a driven superconducting coplanar waveguide resonator operated in the quantum regime, kappa T-B << hw. The resonator is terminated by a tunable inductance that provides a Kerr-type nonlinearity. We detected the output field quadratures at frequencies near the fundamental mode, omega/2 pi similar to 5 GHz, when driving the resonator with a current at 3 omega, with amplitude exceeding an instability threshold. We observed three stable radiative states with equal amplitudes, phase shifted by 2 pi/3 rad, red detuned from the fundamental mode. The down-conversion from 3 omega to omega is strongly enhanced by near- resonant excitation of the second mode of the resonator and the cross- Kerr effect. Our experimental results are in quantitative agreement with a model for the driven dynamics of two coupled modes.
TL;DR: In this paper, the effective optical switching property of Mach-Zehnder interferometer (MZI) utilizing optical Kerr effect has been precisely reported suitably assisted with an analytical approach.
Abstract: The effective optical switching property of Mach–Zehnder interferometer (MZI) utilizing optical Kerr effect has been precisely reported suitably assisted with an analytical approach in this paper. MZI plays the role of the fundamental building block in the designing of intricate combinational circuit by employing Kerr effect. This paper constitutes ultra-compact design of one-bit magnitude comparator along with its mathematical analysis. The analysis of device is justified through MATLAB and finite-difference time-domain (FDTD) method.
TL;DR: The framework developed here sheds light onto the details of the time-resolved MOKE technique and contributes to the understanding of the interplay between ultrafast laser-induced optical and magnetic effects.
Abstract: We discuss fundamental aspects of laser-induced ultrafast demagnetization probed by the time-resolved magneto-optical Kerr effect (MOKE). Studying thin Fe films on MgO substrate in the absence of electronic transport, we demonstrate how to disentangle pump-induced variations of magnetization and magneto-optical coefficients. We provide a mathematical formalism for retrieving genuine laser-induced magnetization dynamics and discuss its applicability in real experimental situations. We further stress the importance of temporal resolution achieved in the experiments and argue that measurements of both time-resolved MOKE rotation and ellipticity are needed for the correct assessment of magnetization dynamics on sub-picosecond timescales. The framework developed here sheds light onto the details of the time-resolved MOKE technique and contributes to the understanding of the interplay between ultrafast laser-induced optical and magnetic effects.
TL;DR: The coupled mode formalism is generalized to study the generation of frequency combs in microresonators with simultaneous Raman and Kerr nonlinearities and it is revealed that the Raman scattering induces a strong instability of the platicon pulses associated with the Kerr effect and normal dispersion.
Abstract: We generalize the coupled mode formalism to study the generation of frequency combs in microresonators with simultaneous Raman and Kerr nonlinearities and investigate an impact of the former on the formation of frequency combs and dynamics of platicons in the regime of the normal group velocity dispersion. We demonstrate that the Raman effect initiates generation of sidebands, which cascade further in four-wave mixing and reshape into the Raman-Kerr frequency combs. We reveal that the Raman scattering induces a strong instability of the platicon pulses associated with the Kerr effect and normal dispersion. This instability results in branching of platicons and complex spatiotemporal dynamics.
TL;DR: In this paper, the authors obtained the dark, bright, dark-bright or combined optical and singular solitons to the perturbed nonlinear Schrodinger-Hirota equation (SHE) with spatio-temporal dispersion (STD) and Kerr law nonlinearity in optical fibers.
TL;DR: In this article, the magnetic and electric orders are further coupled to optical excitations, leading to an Electric tuning of the Magneto-Optical Kerr effect (EMOKE), which can be switched by reversal of both ferroelectric and magnetic polarization only.
Abstract: Hybrid organic–inorganic compounds attract a lot of interest for their flexible structures and multifunctional properties. For example, they can have coexisting magnetism and ferroelectricity whose possible coupling gives rise to magnetoelectricity. Here using first-principles computations, we show that, in a perovskite metal–organic framework (MOF), the magnetic and electric orders are further coupled to optical excitations, leading to an Electric tuning of the Magneto-Optical Kerr effect (EMOKE). Moreover, the Kerr angle can be switched by reversal of both ferroelectric and magnetic polarization only. The interplay between the Kerr angle and the organic–inorganic components of MOFs offers surprising unprecedented tools for engineering MOKE in complex compounds. Note that this work may be relevant to acentric magnetic systems in general, e.g., multiferroics.
TL;DR: In this paper, the authors combined ferromagnetic resonance and the magneto-optical Kerr effect for significant electric-field manipulation of PMA in multiferroic multilayers containing cobalt.
Abstract: Voltage control of perpendicular magnetic anisotropy (PMA) is a promising approach for high-density, lightweight, energy-efficient information storage. Electric-field regulation of PMA in conventional multiferroic laminates is difficult, though, since the voltage-induced magnetic anisotropy is relatively small. This study combines ferromagnetic resonance and the magneto-optical Kerr effect for significant electric-field manipulation of PMA in multiferroic multilayers containing cobalt. Along the way, the authors also gain interesting insight about the instability of Co orbital moments near a critical transition.
TL;DR: In this article, an experimental method, based on a motorized analyzer, is introduced which allows to compensate the Faraday contributions, thus leading to pure MOKE loops, which is the basis for loop interpretation.
Abstract: The measurement of MOKE (Magneto-Optical Kerr Effect) magnetization loops in a wide-field Kerr microscope offers the advantage that the relevant domain images along the loop can be readily recorded. As the microscope's objective lens is exposed to the magnetic field, the loops are usually strongly distorted by non-linear Faraday rotations of the polarized light that occur in the objective lens and that are superimposed to the MOKE signal. In this paper, an experimental method, based on a motorized analyzer, is introduced which allows to compensate the Faraday contributions, thus leading to pure MOKE loops. A wide field Kerr microscope, equipped with this technology, works well as a laser-based MOKE magnetometer, additionally offering domain images and thus providing the basis for loop interpretation.
TL;DR: In this article, a novel all-optical XNOR gate was proposed, which combines the nonlinear Kerr effect with photonic-crystal ring resonators (PCRRs).
Abstract: A novel all-optical XNOR gate is proposed, which combines the nonlinear Kerr effect with photonic-crystal ring resonators (PCRRs). The total size of the proposed optical XNOR gate based on photonic crystals with a square lattice of silicon rods is equal to 35 × 21 ?m. The proposed structure has a bandgap in the range from 0.32 to 0.44. To confirm the operation and feasibility of the overall system use is made of analytical and numerical simulation using the dimensional finite difference time domain (FDTD) and plane wave expansion (PWE) methods.
TL;DR: This work coherently combines two sequences of single photon addition and subtraction to induce a nonlinear phase shift at the single photon level and probes the induced nonlinearity with weak coherent states and characterize the output non-Gaussian states with quantum state tomography.
Abstract: Strong nonlinearity at the single photon level represents a crucial enabling tool for optical quantum technologies. Here we report on experimental implementation of a strong Kerr nonlinearity by measurement-induced quantum operations on weak quantum states of light. Our scheme coherently combines two sequences of single photon addition and subtraction to induce a nonlinear phase shift at the single photon level. We probe the induced nonlinearity with weak coherent states and characterize the output non-Gaussian states with quantum state tomography. The strong nonlinearity is clearly witnessed as a change of sign of specific off-diagonal density matrix elements in the Fock basis.
TL;DR: In this article, the authors investigated the possibility of swapping entanglement swapping between two independent nonperfect cavities consisting of an atom with finite lifetime of atomic levels (as two independent sources of dissipation), which interacts with a quantized electromagnetic field in the presence of detuning and Kerr medium.
Abstract: In this paper, we investigate the possibility of entanglement swapping between two independent nonperfect cavities consisting of an atom with finite lifetime of atomic levels (as two independent sources of dissipation), which interacts with a quantized electromagnetic field in the presence of detuning and Kerr medium. In fact, there is no direct interaction between the two atoms, therefore, no entanglement exists between them. We use the Bell state measurement performed on the photons leaving the cavities to swap the entanglement stored between the atom-fields in each cavity into atom-atom. Our motivation comes from the fact that two-qubit entangled states are of great interest for quantum information science and technologies. We discuss the effect of the initial state of the system, the detuning parameter, the Kerr medium and the two dissipation sources on the swapped entanglement to atom-atom. We interestingly find that when the atomic decay rates and photonic leakages from the cavities are equal, our system behaves as an ideal system with no dissipation. Our results show that it is possible to create a long-living atom-atom maximally entangled state in the presence of Kerr effect and dissipation; we determine these conditions in detail and also establish the final atom-atom Bell state.
24 Mar 2017
TL;DR: Chen et al. as discussed by the authors showed that by substituting the electric field of modern electronics by the MV/cm field of a single-cycle THz laser pulse, the electrooptical gating process can be driven orders of magnitude faster, at THz frequencies.
Abstract: Polarization switching of picosecond laser pulses is a fundamental concept in signal processing [C. Chen and G. Liu, Annu. Rev. Mater. Sci. 16, 203 (1986); V. R. Almeida et al., Nature 431, 1081 (2004); and A. A. P. Pohl et al., Photonics Sens. 3, 1 (2013)]. Conventional switching devices rely on the electro-optical Pockels effect and work at radio frequencies. The ensuing gating time of several nanoseconds is a bottleneck for faster switches which is set by the performance of state-of-the-art high-voltage electronics. Here we show that by substituting the electric field of several kV/cm provided by modern electronics by the MV/cm field of a single-cycle THz laser pulse, the electro-optical gating process can be driven orders of magnitude faster, at THz frequencies. In this context, we introduce diamond as an exceptional electro-optical material and demonstrate a pulse gating time as fast as 100 fs using sub-cycle THz-induced Kerr nonlinearity. We show that THz-induced switching in the insulator diamond i...
TL;DR: In this paper, a reliable and original experimental technique based on the analysis of beam self-trapping to measure ultrafast optical nonlinearities in planar waveguides is presented.
TL;DR: The comparison between the experimental data and the theoretical approach indicates that photon-energy dependent transport processes play a major role in this time-resolved magneto-optical Kerr effect setup.
Abstract: Magnetization dynamics on a femtosecond timescale has been observed for a huge variety of magnetic structures. However, the influence of different excitation photon energies has not been studied in detail yet. In our time-resolved magneto-optical Kerr effect setup we excite a Nickel bulk system with 1.55 and 3.1 eV, respectively, leading to different remagnetization dynamics depending on the chosen photon energy. Furthermore we complement our experimental data with a theoretical approach applying appropriate Boltzmann collision integrals including the density of states of Nickel. The comparison between the experimental data and the theoretical approach indicates that photon-energy dependent transport processes play a major role in this setup.