Kerr Effect Research Articles

Broadband Enhancement of Magneto-Optical Effects in Hybrid Waveguide-Plasmonic Surfaces for Sensing.

Conventional magnetophotonic nanostructures typically function within narrow wavelength and incident angle ranges, where resonance is observed and magneto-optical (MO) effects are amplified. Expanding these operational ranges may allow for improved applications, including in (bio)sensing devices. In this study, we describe a hybrid magnetoplasmonic waveguide grating (HMPWG) in which the coupling of plasmonic resonances and waveguide modes leads to enhanced MO effects and sensitivity, according to full-wave electromagnetic simulations. High transverse magneto-optical Kerr effect (TMOKE) signals were observed for the full range of wavelengths and angles investigated, i.e., for θinc ≥ 1° and 500 nm ≤ λ ≤ 850 nm. As a proof-of-concept we verified that using the HMPWG nanostructure with an aqueous solution as superstrate one may obtain a sensitivity in variation of the refractive index unit (RIU) of S = 166°/RIU and S = 230 nm/RIU in angle and wavelength interrogation modes, respectively. Upon comparing with conventional magnetoplasmonic gratings, which only enable excitation of plasmonic resonances, we demonstrate that HMPWG nanostructures can be further optimized to reach not only high sensitivity but also high resolution in sensing and biosensing.

Magneto-optical Kerr effect of noncollinear antiferromagnetic Mn3Ir films

We present the magneto-optical Kerr effect (MOKE) of (111)-oriented antiferromagnetic L12-Mn3Ir films epitaxially grown on MgO (111) substrates. We observed that the amplitude and sign of the polar MOKE change depending on the growth temperature. The Mn3Ir films grown at 800 and 600 °C have rotation angles of 41.6 and −4.6 mdeg and ellipticity angles of −15.3 and 9.1 mdeg, respectively. Residual strains owing to heteroepitaxial growth on the order of a few tenths of a percent can play a critical role in determining the amplitude and sign of the MOKE of a noncollinear antiferromagnet, unlike ferromagnets.

Polar magneto-optical Kerr effect spectroscopy with a microscope arrangement for studies on 2D materials.

We describe a setup for magneto-optical Kerr effect (MOKE) spectroscopy suitable for Kerr rotation (ϕ) and ellipticity (η) measurement on microscopic samples, such as flakes of two-dimensional materials. A spatial resolution of ∼25μm, limited by the demagnified monochromator exit slit image, was achieved. The use of mirrors allows for measurement in polar MOKE geometry with a conventional electro-magnet, without requiring holes in the magnet pole pieces. The microscope-like optics also has a 90° twisted periscope arrangement of two mirrors that helps transport light without change in its circular polarization state. A Jones matrix analysis of the setup brings out the influence of the beam-splitter on the measured signals. Its correction requires the ellipsometry parameters of the beam-splitter in transmission mode, which were measured separately. The working of the setup is tested by measuring the ϕ and η spectra of 2H-WS2 flakes at low temperature, verifying them using Kramers-Kronig analysis and extracting the Landé g-factor of the ground state exciton from them.

Toward Machine-Learning-Accelerated Design of All-Dielectric Magnetophotonic Nanostructures.

All-dielectric magnetophotonic nanostructures are promising for integrated nanophotonic devices with high resolution and sensitivity, but their design requires computationally demanding electromagnetic simulations evaluated through trial and error. In this paper, we propose a machine-learning approach to accelerate the design of these nanostructures. Using a data set of 12 170 samples containing four geometric parameters of the nanostructure and the incidence wavelength, trained neural network and polynomial regression algorithms were capable of predicting the amplitude of the transverse magneto-optical Kerr effect (TMOKE) within a time frame of 10-3 s and mean square error below 4.2%. With this approach, one can readily identify nanostructures suitable for sensing at ultralow analyte concentrations in aqueous solutions. As a proof of principle, we used the machine-learning models to determine the sensitivity (S = |Δθres/Δna|) of a nanophotonic grating, which is competitive with state-of-the-art systems and exhibits a figure of merit of 672 RIU-1. Furthermore, researchers can use the predictions of TMOKE peaks generated by the algorithms to assess the suitability for experimental setups, adding a layer of utility to the machine-learning methodology.

Strong terahertz pulse induced Pockels and Kerr effect in crystalline quartz for ultrafast pulse switching

Ultrafast pulse switching is one of the key elements for ultrahigh speed communication technology. We study the terahertz (THz) induced birefringence response on the laser pulse through the quartz with different THz electric field strength. The magnitude of the observed Pockels signals scales linearly with the THz field amplitude, while the Kerr signals scale quadratically with the THz field amplitude. We demonstrate that the quartz is a good candidate for polarization modulation of 800 nm laser pulse, which has the advantages of low-cost, large bandgap, and negligible dispersion. Furthermore, our investigation finds application beyond ultrafast polarization switching, and the THz-induced polarization gating technique works as a tool for intense THz pulse detection.

Insights into reduction of hysteresis in (Mn, Fe)2(P, Si) compounds by experimental approach and Landau theory

The giant magnetocaloric effect in (Mn, Fe)2(P, Si) based alloys arises from a magnetoelastic ferromagnetic-paramagnetic (FM-PM) phase transition accompanied by a large thermal hysteresis. The thermal hysteresis leads to an undesirable irreversibility of the magnetocaloric effect (MCE) during cyclic operation, impeding the practical application in solid-state magnetic refrigeration. Here, we present pre-existing PM nuclei play a role in reducing hysteresis. A combinatorial analysis, using in situ X-ray diffraction (XRD) and magneto-optical Kerr effect (MOKE) microscopy, reveals that the residual PM phases at the ferromagnetic state of the compound acts as the nuclei for the growth of the PM phases. This is kinetically favorable for the FM-PM phase transition and contributes to a smaller hysteresis from an extrinsic perspective. In addition, the smaller changes in the lattice constants during the phase transition indicates a weakened first-order phase transition. Through a combined effect of intrinsic and extrinsic contributions, a giant MCE in the magnetic entropy change of 16 J kg–1 K−1 under 2 T and a low thermal hysteresis of 3.0 K were achieved in a basic Mn–Fe–Si–P quaternary system for room temperature applications. Furthermore, based on Landau theory and experimentally obtained data, we established an H-T phase diagram and unveiled the crucial role of the magnetoelastic coupling in manipulating thermal hysteresis. Overall, the findings in this work offer a strategy to mitigate hysteresis while retaining a large MCE through extrinsic control.

Optical fiber sensor based on magneto-optical surface plasmon resonance with ultra-high figure of merit

Compared to surface plasmon resonance (SPR), the sensors based on the magneto-optical SPR (MOSPR) technique have much higher figure-of-merit (FOM). However, there are no reports about applying MOSPR in the optical fiber structure now. In this work, a novel D-shaped optical fiber sensor based on the MOSPR technique is proposed. The D-shaped optical fiber is coated with a thin silver film and a magneto-optical (MO) material film of Cerium-doped Yttrium-Iron garnet (CeYIG). By applying a magnetic field on the sensing region, the magneto-optical Kerr effect (MOKE) of the CeYIG layer and the related MOSPR phenomenon could be excited when appropriate light is transmitted in the proposed optical fiber sensor. The influence of the structural parameters including the residual cladding thickness, silver and MO material film thicknesses are analyzed theoretically by the finite element method (FEM). With the optimal parameters, the sensor achieves the sensitivity of 5304 nm RIU−1. Since the peak width of MOSPR spectra is much narrower than that of the SPR spectra, the FOM of the sensor is largely enhanced to 3864 RIU−1 on average and 13260 RIU−1 in maximum, which surpasses the optical fiber SPR sensors vastly. The miniaturized and simple design of the D-shaped optical fiber MOSPR sensor, coupled with the ultra-high FOM, offers itself great potential in biochemical sensing applications.

Microwave quantum illumination: enhanced azimuth detection with cavity magnonics

Most current microwave quantum illumination techniques rely on hybrid quantum systems to detect the presence of targets. However, real-world radar tasks are considerably more intricate than this simplistic model. Accurately determining physical attributes such as object speed, position, and azimuth is also essential. In this study, we explore azimuth detection using a quantum illumination approach based on a cavity-optomagnonics system and analyze the accuracy of azimuth detection in this framework. Our results indicate that this approach significantly outperforms classical microwave radar in azimuth detection within the parameters of current existing experiments. Additionally, we investigate the impact of Kerr nonlinearity of the YIG sphere on azimuth detection accuracy, revealing a clear improvement with the incorporation of Kerr nonlinearity.

Dark, bright and singular optical solitons for Biswas–Milovic equation with Kerr and dual power law nonlinearities

This paper attains cubic-quartic optical solitons of the Biswas–Milovic equation with dual power law and Kerr law nonlinearities. Dark, bright, singular and combo-singular solitons solutions are obtained with the F-expansion method. The solutions gained in our this work are newer than the obtained solutions using different method before this work in the literature. In order to better convey the physical significance of the solutions, we also include 2D and 3D graphics. The computational software MATHEMATICA is the helping tool for visualizing and analyzing the derived solutions.

Mid-Infrared Supercontinuum Generation in Highly Nonlinear Chalcogenide Fibers

Interest in mid-infrared broadband laser light sources has surged due to applications in trace gas detection, free-space communications, and countermeasures. Progress in supercontinuum generation leverages fiber-based near-infrared and bulk-optic mid-infrared pump sources. In this paper, the Generalized Nonlinear Schrödinger Equation has been solved, using the Split Step Fourier Method, to simulate the pulse propagation and mid-infrared supercontinuum generation, inside a fiber composed of highly nonlinear As2Se3/As2S3 chalcogenide glass. The effect of various parameters, including fiber nonlinearity, Group Velocity Dispersion (GVD), input power and pulse-width, anomalous and normal dispersion pumping regime, etc. on the output supercontinuum bandwidth has been extensively studied. A tapered chalcogenide fiber is modeled to facilitate continuous simultaneous modification of the GVD and the Kerr nonlinearity parameter. Pumping the waveguides with 230-fs secant pulses at a peak power of 4.2-kW yields a mid-IR supercontinuum extending from [Formula: see text] to [Formula: see text] micrometers.

Spectrally-broadened femtosecond vortex beams in air with longitudinal pressure distribution

The spectral broadening of femtosecond vortex beams in air with different longitudinal pressure distributions is studied numerically. By introducing a symmetrical pressure distribution, a sufficiently broadened spectrum while preserving vortex characteristics of the beam for different input energies can be generated. The proposed pressure distribution involves an increase during the self-focusing stage, followed by a flat-top and symmetric decrease. This approach takes advantage of the mechanism that the strong Kerr nonlinearity in the high-pressure filamentation region results in a broader spectrum towards the blue side through the self-phase modulation and ionization, while the weak Kerr nonlinearity in the low-intensity regions before and after filamentation with low pressure leads to the decrease of the intensity fluctuation and the preservation of vortex characteristics due to weak modulation instability. Consequently, the resulting vortex beam exhibits a broad enough spectrum, and the transform-limit duration reaches a single cycle. This study provides a valuable approach for generating single-cycle vortex beams.

Spin–wave dynamics in perpendicularly magnetized antidot multilayers

Using all-optical time-resolved magneto-optical Kerr effect measurements we demonstrate an efficient modulation of the spin–wave (SW) dynamics via the bias magnetic field orientation around nanoscale diamond shaped antidots that are arranged on a square lattice within a [Co(0.75 nm)/Pd(0.9 nm)]8 multilayer with perpendicular magnetic anisotropy (PMA). Micromagnetic modeling of the experimental results reveals that the SW modes in the lower frequency regime are related to narrow shell regions around the antidots, where in-plane (IP) domain structures are formed due to the reduced PMA, caused by Ga+ ion irradiation during the focused ion beam milling process of antidot fabrication. The IP direction of the shell magnetization undergoes a striking change with magnetic field orientation, leading to the sharp variation of the edge localized (shell) SW modes. Nevertheless, the coupling between such edge localized and bulk SWs for different orientations of bias field in PMA systems gives rise to interesting Physics and attests to new prospects for developing energy efficient and hybrid-system-based next-generation nanoscale magnonic devices.

Fano resonances in dielectric metasurfaces with hemispherical voids: Effect on the optical Kerr nonlinearity

The optical behavior of the square lattices of the hemispherical nanovoids on the surface of the high-refractive-index all-dielectric slabs in the visible range is studied numerically using gallium phosphide as an example. There exist Fano resonances for these metasurfaces for a limited range of thicknesses. The Fano resonances are caused by the interference between the Mie-type scattering resonances of surface pattern elements and the Fabry–Pérot modes of the slabs. The maximum enhancements of the optical Kerr nonlinearity with respect to the bulk material are revealed at the Fano resonances, in particular, for the thinnest nanostructures. Interestingly, no positive correlation between the quality factor and the enhancement of the optical Kerr effect of the metasurface at the Fano resonances is observed.

Generation of optical dromions to generalized stochastic nonlinear Schrödinger equation with Kerr effect and higher order nonlinearity

Stochastic nonlinear Schrödinger equation is a mathematical model, used in the study of complex systems especially nonlinear optics and quantum mechanics. It explains the evolution of a quantum field with stochastic and nonlinear terms. A stochastic or random process is a mathematical representation that outlines the progression of a system in a way that incorporates probability. This is in contrast to a deterministic process, where the future states are strictly defined by initial conditions. In mathematical model, stochastic term is usually represent by variable or a function that involves random variable or a noise. In this paper, we study the generalized nonlinear Schrödinger equation by adding stochastic term for the first time to retrieve different types of optical solitons. To the best of our knowledge, no one work on this model with stochastic term. Our aim is to find optical solitons like bright and dark solitons, also solitary wave solutions for this model like bell type, hyperbolic functions, Jacobi Elliptic Function, Weierstrass Elliptic Function, periodic and rational solutions. These solutions will be obtained using the sub-ode method, subject to certain constraint conditions. Finally, we will use Jupyter as a machine learning tool and also mathematica to plot some obtained solutions in various dimensions like 3D, 2D and contour plots by using some libraries of PYTHON like numpy, scipy.integrate and matplotlib.pyplot. For the first time, we use this approach for this model and our results are new and novel [1].

Picosecond Imaging Of Bubbly Flows

Despite their ubiquity, bubbly flows are notoriously challenging to instrument. In high-void fractions, most optical measurement techniques fail due to intense scattering and occlusion. Ultrafast imaging with picosecond exposure times offers an opportunity, allowing measurements before scattering obscures the field of view. Furthermore, detecting the time of arrival of photons allows measurement of bubble sizes, even for those partially occluded. Through implementing the Optical Kerr Effect (OKE), using a 70 fs 800 nm pulsed laser and a Carbon Disulfide cell, images are acquired with an exposure of 2.9 ps. Gating these images with an optical delay stage further allows the decomposition of scenes with 33 fs time increments. Proof of concept is demonstrated by applying this approach to static scenes of submerged bubbles at low and high void fractions. The experimental temporal decomposition shows the arrival of photons that travel through different media (air, water, and glass) and those scattered within the turbid media. A new visualization is presented to display this breakdown concisely, the Temporally Tagged Shadowgraph (TTS), presenting the time of arrival with the context of position and surroundings. Bubble sizes are measured using this temporal information and through edge detection, with good agreement for single unoccluded bubbles. With polydisperse bubble plumes, time delay-based measurements tend to overestimate bubble diameter; however, this could also be due to greater uncertainty in edge detection with occlusion. This demonstrates the potential of Ultrafast Imaging when it comes to probing high-void fraction flows. By further shortening exposure times and improving the robustness of processing algorithms, the scope of applicability of this technique can be widened.

Optical fibers with a frequency-dependent Kerr nonlinearity: Theory and applications

This review provides a detailed discussion of both the mathematical treatment and the impact of a frequency-dependent Kerr nonlinearity on the propagation of short pulses in optical fibers. We revisit the theoretical framework required to deal with the frequency dependence of the nonlinear response without incurring any physical inconsistencies, such as the non-conservation of the photon number. Then, we point out the role of the zero-nonlinearity wavelength, its interplay with the zero-dispersion wavelength, and their influence on evolution of optical pulses in optical fibers, specifically by looking at soliton propagation and the ensuing generation of Cherenkov radiation. Finally, by means of a space–time analogy involving the collision of a weak control pulse and an intense soliton, we describe an all-optical switching scheme in the presence of a zero-nonlinearity wavelength within a photon-conserving framework.

Kerr nonlinearity induced nonreciprocity in dissipatively coupled resonators

Nonlinearity-induced nonreciprocity is studied in a system comprising two resonators coupled to a one-dimensional waveguide when the linear system does not exhibit nonreciprocity. The analysis is based on the Hamiltonian of the coupled system and includes the dissipative coupling between the waveguide and resonators, along with the input-output relations. We consider a large number of scenarios which can lead to nonreciprocity. We pay special attention to the case when the linear system does not exhibit nonreciprocal behavior. In this case, we show how very significant nonreciprocal behavior can result from Kerr nonlinearities. We find that the bistability of the nonlinear system can aid in achieving large nonreciprocity. Additionally, we bring out nonreciprocity in the excitation of each resonator, which can be monitored independently. Our results highlight the profound influence of nonlinearity on nonreciprocal behavior, offering an avenue for controlling light propagation in integrated photonic circuits. Nonlinearity-induced nonreciprocity would lead to significant nonreciprocity in quantum fluctuations when our system is treated quantum mechanically. Published by the American Physical Society 2024

Anomalous to normal dispersion nonlinear optical dephasing switch in electromagnetically induced transparency using a Kerr effect

The atomic decoherence effect (DE) on a Kerr nonlinear (KNL) electromagnetically induced transparency (EIT)is studied in a Δ system. The DE between the ground state hyperfine levels is caused by the dephasing rate γ d which dramatically modifies the medium response. It controls the normal dispersive region which shows steep positive slopes for linear response at the line center while the nonlinear response experiences steep negative slopes for low γ d . The microwave field strength and γ d modify the nonlinear response from the anomalous dispersion to normal dispersion. The calculations show that room-temperature atoms are used to quantify the quantum interference (QI) on linear and nonlinear absorption with γ d . The EIT spectrum explores the understanding of the subluminal and superluminal wave propagation of probe signal and this study opens a new pathway for the understanding of the QI devices and their nonlinearities based on EIT.

Phase sensitive slow light in semiconductor quantum dots

This article presents a theoretical investigation of phase-controlled propagation of slow light under an electromagnetically induced transparency window in a multilayered one-dimensional photonic crystal with semiconductor quantum dot nanostructures as defects. To achieve the electromagnetically induced transparency window, a setup utilizes a faint probe laser pulse alongside two powerful control laser beams arranged in a closed-loop cascade configuration. In this arrangement, a significant Kerr nonlinearity, approximately on the scale of ∼10−13m2/V2, is discerned within the quantum dot nanostructures at a probe wavelength of 1.55 μm. It is observed that both the amplitude and the phase relationship of the control Rabi frequencies play crucial roles in governing the dynamics of the group velocity of the probe field in the quantum dot nanostructures. Under the regime of electromagnetically induced transparency, the group velocity of the probe field is significantly reduced, approximately by a factor of 103 times as compared to the light speed in free space. These findings hold promise for potential applications in nonlinear optics.

Styrene monomer as potential material for design of new optoelectronic and nonlinear optical polymers: density functional theory study.

Using density functional theory, we have studied the intrinsic properties of styrene. First, we determine the optimized structures, structural parameters and thermodynamic properties to make our simulations more realistic to experimental results and check the stability. Second, we investigate optoelectronic, electronic and global descriptors, transport properties of holes and electrons, natural bond orbital analysis, absorption and fluorescence properties. Finally, we study nonlinear optical (NLO) properties: first- and second-order hyperpolarizability, second and third-order optical susceptibilities, hyper-Rayleigh scattering hyperpolarizability, electro-optical Pockel effect, direct current Kerr effects and quadratic refractive index. The bandgap energy E g = 5.146 eV and dielectric constant show that styrene is a good insulator with an average electric field value of 4.43 × 108 Vm-1. Thermodynamic findings show that our molecule is thermodynamically and chemically stable. Electron and hole reorganization energies of 0.393 and 0.295 eV, respectively, show that styrene is more favourable to hole transport than electron transport. Styrene is transparent with linear refractive index n = 1.750 and quadratic n 2 = 1.748 × 10-20 m2 W-1. At the NLO, styrene has a non-zero value of which confirms the existence of first-order NLO activity. Globally the study shows that the styrene monomer is suitable for the architecture design of new polymer materials for NLO applications and optoelectronic by functionalization.