Kerr Effect Research Articles

Nonlinear eigen modes in optical media supported by cubic and quintic nonlinearities with Parity-Time symmetric hyperbolic complex potential

This work explored optical waves in different nonlinear media, specifically in self-focusing cubic–quintic media, and investigated how these waves evolve and maintain their characteristics under the influence of various factors such as nonlinear interactions, diffraction, and Parity-Time (PT) symmetric complex field with hyperbolic real and imaginary distributions. We explored how the range of the complex field parameter over which PT-symmetry collapse occurs is modified by the order of the nonlinear function, modulation strength that makes up the potential, the separation between peaks, and the width of the PT-symmetric field. A comparison of the soliton solutions with Kerr and quintic nonlinearities clarifies that the span of sustainable PT-symmetry in the self-focusing medium expands with the higher order nonlinear function. We discussed the propagation-related nonlinear evolutions of unstable and robust PT solitons. The conditions necessary for sustained soliton in PT-symmetric and broken PT-symmetric domains were identified by the study of the linear stability of solitons.

Exceptional point proximity-driven mode-locking in coupled microresonators.

We show theoretically and numerically that mode-locking is feasible with a coupled-cavity system with gain and loss, notably, without any natural saturable absorber. We highlight that in the vicinity of the exceptional point, system Q exhibits substantial modulation even with minor refractive index changes and a minimal Kerr effect contribution. Leveraging this unique behavior, we propose an unprecedented approach wherein the lossy auxiliary cavity functions as an efficient artificial saturable absorber, thus facilitating mode-locking. This approach is not only novel, but also presents considerable advantages over conventional systems where both gain and saturable absorption are contained within a single microcavity. These benefits include reduced operational power and ease of post-adjustment, achievable through the manipulation of the coupling strength between the two microcavities.

A quantum sensing metrology for magnetic memories

Magnetic random access memory (MRAM) is a leading emergent memory technology that is poised to replace current non-volatile memory technologies such as eFlash. However, controlling and improving distributions of device properties becomes a key enabler of new applications at this stage of technology development. Here, we introduce a non-contact metrology technique deploying scanning NV magnetometry (SNVM) to investigate MRAM performance at the individual bit level. We demonstrate magnetic reversal characterization in individual, <60 nm-sized bits, to extract key magnetic properties, thermal stability, and switching statistics, and thereby gauge bit-to-bit uniformity. We showcase the performance of our method by benchmarking two distinct bit etching processes immediately after pattern formation. In contrast to ensemble averaging methods such as perpendicular magneto-optical Kerr effect, we show that it is possible to identify out of distribution (tail-bits) bits that seem associated to the edges of the array, enabling failure analysis of tail bits. Our findings highlight the potential of nanoscale quantum sensing of MRAM devices for early-stage screening in the processing line, paving the way for future incorporation of this nanoscale characterization tool in the semiconductor industry.

Formation of high-power microwave dissipative soliton combs based on reactive electron–wave interaction

We theoretically demonstrate the possibility of implementing high-power repetitively pulsed microwave radiation sources based on an analogy with the formation of optical dissipative soliton combs in microresonators with Kerr nonlinearity pumped by laser radiation. A similar mechanism can arise due to electron–wave interaction in a microwave-pumped high-Q resonator when, with near-zero synchronism, detuning, amplification, and absorption are negligible, and the driving electron beam primarily acts as a medium with reactive nonlinearity. The required physical parameters are estimated for observing Ka-band dissipative soliton combs based on an undulator mechanism of electron–wave interaction in a gyrotron-pumped resonator.

Controlling the frequencies of photons emitted by a single quantum dot in a one-dimensional photonic crystal

Subject of study. A single InAs quantum dot in a one-dimensional photonic crystal based on GaAs is examined. Aim of study. The aim of this study is to develop a method for controlling photon emission frequencies from a single quantum dot within a one-dimensional photonic crystal based on changes in the electromagnetic mass of an electron in the photonic crystal medium. Method. The proposed approach leverages the effect of changing the electromagnetic mass of an electron in the photonic crystal medium, manifesting as corrections to electron energy levels depending on the optical density of the medium. To control this density, the injection of free charge carriers and the quadratic electro-optic Kerr effect are proposed. Main results. The feasibility of in situ control of photon emission frequencies from a quantum dot was demonstrated using quantum transitions between the p- and s-states of a hydrogen-like InAs quantum dot situated in the air voids of a one-dimensional GaAs photonic crystal. This control is achieved through the effect of changing the electromagnetic mass of an electron, as well as tuning the refractive index of the photonic crystal via free charge carrier injection and the electro-optic Kerr effect. Calculations indicate that the photon energy control range available in experiments is limited to several tens of microelectronvolts, restricting practical applicability, and the observed displacement effect is smaller than experimentally recorded values. However, the energy level displacement, influenced by the quantum electrodynamic effect under investigation, exhibits a quadratic dependence on the refractive index of the material forming the photonic crystal. Consequently, the method is expected to scale significantly with increasing optical density. Such photonic crystals could be constructed using metamaterials with a high refractive index. Practical significance. The findings of this study, centered on developing a method for controlling photon emission frequencies from a single quantum dot in a one-dimensional photonic crystal, lay the groundwork for photon-emitter interfaces. These interfaces will incorporate key quantum functionalities, including photonic qubits, single-photon light sources, and nonlinear quantum photon-photon gates.

Nonlinear localized states near the interface with nonlinear response between the medium with a parabolic index spatial profile and Kerr-type medium

The interface with nonlinear response separating the parabolic graded-index and the Kerr nonlinear media are considered. Exact solutions to the nonlinear Schrödinger equation with nonlinear short-range potential and a parabolic spatial profile are found applying to the theoretical description of the stationary states localized near interface with nonlinear properties. Localized states with continuous/discrete energy spectrum are described by the Whittaker function/Hermite polynomials in the medium with a parabolic profile of characteristic and the hyperbolic cosine (sine) in the medium with a self-focusing/defocusing Kerr nonlinearity. The field localization length is wider in the case of a self-focusing nonlinearity than in the case of a defocusing one. The maximum of the wave function is located in a nonlinear medium in the case of a self-focusing nonlinearity and at the interface in the case of a defocusing one. It is shown the possibility of a motion closer to the interface (or away from it) the maximum intensity of the localized state by changing the values of the interface response parameters at the fixed localization energy. A growth of the width of the parabolic graded-index layer adduced an increase in the maximum height of localized states of discrete spectrum and theirs localization length in the graded-index layer, but it had almost no effect on the profile of localized states of the continuous spectrum.

Nonlinear Schrödinger equation for integrated photonics

The foundations of nonlinear optics are revisited, and the formalism is applied to waveguide modes. The effects of loss and dispersion are included rigorously along with the vectorial nature of the modes, and a full derivation of a new version of the nonlinear Schrödinger (NLS) equation is presented. This leads to more general expressions for the group index, for the group-index dispersion (GVD), and for the Kerr coefficient. These quantities are essential for the design of waveguides suitable for, e.g., the generation of optical frequency combs and all-optical switches. Examples are given using the silicon nitride material platform. Specifically, values are extracted for the coefficients of the chi-3 tensor based on measurements of Kerr coefficients and mode simulations.

Relationship between magnetic asymmetry and magnetization in ultrafast transverse magneto-optical Kerr effect spectroscopy in the extreme ultraviolet spectral range

Relationship between magnetic asymmetry and magnetization in ultrafast transverse magneto-optical Kerr effect spectroscopy in the extreme ultraviolet spectral range

Design of a high-resolution magneto-plasmonic biosensor for analyte detection

This paper introduces the design of a magneto-plasmonic refractometric sensor aimed at achieving high resolution. This sensor consists of arrays of gold nanowires and layers of SiO2 and Co6Ag94, where the analyte is placed on the gold nanowires. A p-polarized optical field with a wavelength of 631 nm is used to excite the structure, which is applied in the range of 1° to 45°. A magnetic field is applied to z-axis to create the magneto-optical effect. The reflected optical field of the samples is used to calculate the signal of the transverse magneto-optical Kerr effect, which shows significant changes in the refractive index of the samples and the direction of the magnetic field. The highest displacement is 4°. The highest value of the figure of merit is 3611 RIU−1, and the maximum sensitivity is obtained as 71 °/RIU.

Non-resonant Bragg scattering four-wave mixing at near-visible wavelengths in low-confinement silicon nitride waveguides.

Quantum state coherent frequency conversion processes-such as Bragg-scattering four-wave mixing (BSFWM)-hold promise as a flexible technique for networking heterogeneous and distant quantum systems. In this Letter, we demonstrate BSFWM within an extended (1.2-m) low-confinement silicon nitride waveguide and show that this system has the potential for near-unity frequency conversion in visible and near-visible wavelength ranges. Using sensitive classical heterodyne laser spectroscopy at low optical powers, we characterize the Kerr coefficient (∼1.55 W-1m-1) and linear propagation loss (∼0.0175 dB/cm) of this non-resonant waveguide system, revealing a record-high nonlinear figure of merit (NFM = γ/α ≈ 3.85 W-1) for BSFWM of near-visible light in non-resonant silicon nitride waveguides. We predict how, at high yet achievable on-chip optical powers, this NFM would yield a comparatively large frequency conversion efficiency, opening the door to near-unity flexible frequency conversion without cavity enhancement and resulting bandwidth constraints.

Spin‐Orbit Torque Switching of Magnetization in Ultra‐Thick Ferromagnetic Layers

AbstractCurrent‐induced magnetization switching via spin‐orbit torque (SOT) holds great potential for applications in high‐speed and energy‐efficient magnetic memory and logic devices. In the extensively studied heavy metal/ferromagnet (HM/FM) SOT heterostructures, the thickness of the FM layer is typically restricted to a few nanometers or less due to the rapid spin dephasing, making it challenging to implement thermally stable memory cells with high density. In this study, it is demonstrated that this thickness constraint can be significantly alleviated by utilizing an oxide ferromagnet La0.67Sr0.33MnO3 (LSMO). Through electrical transport and magnetic optical measurements, it is found that the SOT can switch the magnetization in Pt/LSMO heterostructures even at an LSMO thickness of 35 nm, which is one order of magnitude larger than that for metallic FMs, such as CoFeB. Furthermore, based on the FM thickness dependence of the switching current and the domain switching type revealed by magnetic optical Kerr effect imaging (MOKE), a possible picture is proposed to describe the SOT switching in Pt/LSMO, which highlights the critical role of the domain wall propagation in the vertical direction. The work provides valuable insights into the behavior of SOT switching in ultra‐thick FM films, offering new possibilities for their practical applications.

Enhancement of lateral shifts by Kerr nonlinearity, via atom cavity coupling

The susceptibility of a two-level atomic medium enclosed in a cavity is controlled and modified by a control driving field and cavity coupling. The susceptibility of the medium is related to the dielectric function, and reflection & transmission coefficients. The transmission and reflection coefficients are related to Goos–Hänchen Shifts in the reflection and transmission beam. Negative and positive lateral GH-shifts, and Giant shifts in the transmission and reflection beams are investigated under the effect of cavity coupling and Kerr nonlinearity. A giant shift of 2000λ in the reflection and 1000λ in the transmission beam is calculated. It is clear that both modified Giant shifts and lateral shifts are influenced by changes in the refractive index. So it will have potential applications in sensing and trapping of the optical data. The controlled and considerably enhanced GH shift show the importance of utilizing the proposed scheme for the construction of optical sensors and optical devices.

Physics to system-level modeling of silicon-organic-hybrid nanophotonic devices

The continuous growth in data volume has sparked interest in silicon-organic-hybrid (SOH) nanophotonic devices integrated into silicon photonic integrated circuits (PICs). SOH devices offer improved speed and energy efficiency compared to silicon photonics devices. However, a comprehensive and accurate modeling methodology of SOH devices, such as modulators corroborating experimental results, is lacking. While some preliminary modeling approaches for SOH devices exist, their reliance on theoretical and numerical methodologies, along with a lack of compatibility with electronic design automation (EDA), hinders their seamless and rapid integration with silicon PICs. Here, we develop a phenomenological, building-block-based SOH PICs simulation methodology that spans from the physics to the system level, offering high accuracy, comprehensiveness, and EDA-style compatibility. Our model is also readily integrable and scalable, lending itself to the design of large-scale silicon PICs. Our proposed modeling methodology is agnostic and compatible with any photonics-electronics co-simulation software. We validate this methodology by comparing the characteristics of experimentally demonstrated SOH microring modulators (MRMs) and Mach Zehnder modulators with those obtained through simulation, demonstrating its ability to model various modulator topologies. We also show our methodology's ease and speed in modeling large-scale systems. As an illustrative example, we use our methodology to design and study a 3-channel SOH MRM-based wavelength-division (de)multiplexer, a widely used component in various applications, including neuromorphic computing, data center interconnects, communications, sensing, and switching networks. Our modeling approach is also compatible with other materials exhibiting the Pockels and Kerr effects. To our knowledge, this represents the first comprehensive physics-to-system-level EDA-compatible simulation methodology for SOH modulators.

Phase-modulated nonreciprocal photon blockade and transmission via optomechanically induced Kerr nonlinearity

Phase-modulated nonreciprocal photon blockade and transmission via optomechanically induced Kerr nonlinearity

Optical bistability at lower photon number via photon and phonon interaction in the presence of Kerr nonlinearity

Optical bistability is theoretically analyzed in a hybrid optomechanical system consisting of an optical cavity including a Kerr medium and an optomechanical cavity coupled by direct tunnel coupling. The dynamics of the system is described by Heisenberg–Langevin equations. It is numerically shown that there is a critical value of the Kerr coefficient to observe the bistability of the intracavity intensity for a given coupling rate, and the changing of the Kerr coefficient will lead to the changing of the critical point to observe the bistability as well. In addition, the first critical value to observe bistability becomes larger with the increasing coupling rate between the two cavities. It is also demonstrated that the pump beam required to realize the bistable behavior in the blue sideband regime is significantly smaller than that in the red sideband regime. And the mean intracavity photon number is relatively larger in the red sideband case than that in the blue sideband case. It is remarkable to observe that the mean intracavity photon numbers in both cavities are much lower than that in ordinary situations.

High-precision spatiotemporal three-dimensional ultrashort pulse synchronization with optical Kerr effect

In studying the interaction of multiple ultrashort pulses with matter, high requirements are put forward for spatiotemporal synchronization accuracy. Limited by the response time and bandwidth of existing devices, the synchronization of multiple ultrashort pulses still faces significant difficulties. By observing the transient phenomena of the optical Kerr effect, high-precision, three-dimensional (x, y, t) synchronization of ultrashort pulses at different angles was achieved. In the optical Kerr effect, the polarization state of the signal pulse changes only when it coincides with the pump pulse, at which point the signal pulse passes through the analyzer. The changes in the intensity and phase of the signal pulse is positively correlated with the degree of spatiotemporal coincidence. In this study, 10-ps pulses were used in the experiments. By observing the intensity and phase distribution of the signal pulses, a time synchronization accuracy between two pulses of less than 1 ps and spatial synchronization accuracy of ±125 µm and ±3 µm in the x and y directions, respectively, were achieved. Moreover, the synchronization of two pulses at an angle of 90 ° was measured, further proving that the method can achieve the spatiotemporal synchronization of pulses with large angles. Therefore, this method has important application prospects in the study of multi-beam interactions with matter and other ultrafast physical phenomena.

Abundant New Optical Soliton Solutions to the Biswas–Milovic Equation with Sensitivity Analysis for Optimization

This study extensively explores the Biswas–Milovic equation (BME) with Kerr and power law nonlinearity to extract the unique characteristics of optical soliton solutions. These optical soliton solutions have different applications in the field of precision in optical switching, applications in waveguide design, exploration of nonlinear optical effects, imaging precision, reduced intensity fluctuations, suitability for optical signal processing in optical physics, etc. Through the powerful (G′/G, 1/G)-expansion analytical method, a variety of soliton solutions are expressed in three distinct forms: trigonometric, hyperbolic, and rational expressions. Rigorous validation using Mathematica software ensures precision, while dynamic visual representations vividly portray various soliton patterns such as kink, anti-kink, singular soliton, hyperbolic, dark soliton, and periodic bright soliton solutions. Indeed, a sensitivity analysis was conducted to assess how changes in parameters affect the exact solutions, aiding in the understanding of system behavior and informing decision-making, especially in accurately designing or analyzing real-world optical phenomena. This investigation reveals the significant influence of parameters λ, τ, c, B, and Κ on the precise solutions in Kerr and power law nonlinearities within the BME. Notably, parameter λ exhibits consistently high sensitivity across all scenarios, while parameters τ and c demonstrate pronounced sensitivity in scenario III. The outcomes derived from this method are distinctive and carry significant implications for the dynamics of optical fibers and wave phenomena across various optical systems.

Effect of growth conditions on magnetization reversal and magnetic anisotropy in Co2Fe0.5Ti0.5Si quaternary Heusler alloy thin films

Ferromagnetic resonance and magneto-optic Kerr effect (MOKE) techniques are employed to unravel the nature of ‘in-plane’ (IP) magnetic anisotropy and magnetization reversal (MR) processes in magnetron-sputtered 100 nm Co2Fe0.5Ti0.5Si (CFTS) thin films, deposited (and subsequently annealed) at different substrate temperatures (Ts) ranging from 200 °C to 550 °C. By varying TS, the CFTS films are produced with different amounts of anti-site (AS) atomic disorder. Irrespective of the degree of AS disorder, the IP uniaxial magnetic anisotropy (UMA) is prevalent in all the CFTS films. The TS450 and TS500 films, deposited at T S = 450 °C and 500 °C, stand out as they have (i) the least AS disorder, (ii) lowest value (α = 0.0055) of the Gilbert damping constant, (iii) high saturation magnetization ( ≅770 G ) at 300 K, (iv) UMA energy density as high as ≅1.6×104erg/cc at 120 K dropping to ≅1.0×104erg/cc at 300 K, (v) spin-wave stiffness ( D ) at T = 0 K, D0≅175 meVÅ2 and, as in other CFTS films, the electron–magnon interaction is primarily responsible for the thermal renormalization of D . Furthermore, in the TS450 and TS500 films, MOKE hysteresis loops at various angles ( ψH ) that the field makes with the easy axis in the film plane, reveals two mutually exclusive UMAs, UMA1≫UMA2 , with easy axes perpendicular to each other. By contrast, only a single UMA is observed in all the remaining films. When ψH=0∘ , MOKE domain images reveal that, consistent with the uniaxial nature of magnetic anisotropy, an abrupt reversal of magnetization is accompanied by the formation of 180° domains. When ψH = 90°, due to the presence of two UMAs in TS450 and TS500 films, following the field reversal, first the reverse domains nucleate and then grow at the expense of the fundamental domains through field-induced domain wall motion.

Memorizable Electro‐Birefringence Effect Exhibited by Transparent Liquid Crystal/Polymer Composite Materials

AbstractPolymer‐dispersed liquid crystals (PDLCs) with nano‐phase‐separated structures, in which nanometer‐sized liquid crystal (LC) domains are dispersed within a polymer matrix (nano‐PDLCs), are transparent solid materials whose optical properties can be modulated by applying an electric field (E‐field). Because the proportion of LC that can respond to an electric field is small, the specific surface area of the phase‐separated interface of nano‐PDLCs is larger than that of conventional PDLCs, resulting in higher drive voltages than those of conventional PDLCs. To lower the driving voltage of nano‐PDLCs, highly polar LCs (C3DIO) are used with a large dielectric anisotropy (&gt;10000), and prepared nano‐PDLCs using DIO mixtures obtained by mixing them with related compounds as the host LC. Nano‐PDLCs employing DIO mixtures exhibit higher E‐field responsivity than those using conventional LC. In addition, the electro‐optical Kerr coefficient at visible wavelength is significantly high, reaching 10−8 m V−2. Furthermore, nano‐PDLCs using the DIO mixture exhibit a memory effect in which the induced birefringence remains even after the removal of the in‐plane E‐field. Memorized birefringence can be erased by heating or applying an E‐field perpendicular to the substrate surface. Nano‐PDLCs using a DIO mixture can be rewritable electro‐birefringence‐responsive materials that can memorize arbitrary birefringence values.

Nonreciprocal Unconventional Photon Blockade with Kerr Magnons

AbstractNonreciprocal devices, allowing to manipulate one‐way signals, are crucial to quantum information processing and quantum networks. Here a nonlinear cavity‐magnon system is proposed, consisting of a microwave cavity coupled to one or two yttrium–iron–garnet (YIG) spheres supporting magnons with Kerr nonlinearity, to investigate nonreciprocal unconventional photon blockade. The nonreciprocity originates from the direction‐dependent Kerr effect, distinctly different from previous proposals with spinning cavities and dissipative couplings. For a single sphere case, nonreciprocal unconventional photon blockade can be realized by manipulating the nonreciprocal destructive interference between two active paths, via varying the Kerr coefficient from positive to negative, or vice versa. By optimizing the system parameters, the perfect and well‐tuned nonreciprocal unconventional photon blockade can be predicted. For the case of two spheres with opposite Kerr effects, only reciprocal unconventional photon blockade can be observed when two cavity‐magnon coupling strengths Kerr strengths are symmetric. However, when coupling strengths or Kerr strengths become asymmetric, nonreciprocal unconventional photon blockade appears. This implies that two‐sphere nonlinear cavity‐magnon systems can be used to switch the transition between reciprocal and nonreciprocal unconventional photon blockades. This study offers a potential platform for investigating the nonreciprocal photon blockade effect in nonlinear cavity magnonics.