Showing papers on "Kerr effect published in 2019"
TL;DR: The theory of Hawking radiation can be tested in laboratory analogues of black holes by using light pulses in nonlinear fiber optics to establish artificial event horizons and observing that the probe stimulates Hawking radiation, which occurs in a regime of extreme non linear fiber optics where positive and negative frequencies mix.
Abstract: The theory of Hawking radiation can be tested in laboratory analogues of black holes We use light pulses in nonlinear fiber optics to establish artificial event horizons Each pulse generates a moving perturbation of the refractive index via the Kerr effect Probe light perceives this as an event horizon when its group velocity, slowed down by the perturbation, matches the speed of the pulse We have observed in our experiment that the probe stimulates Hawking radiation, which occurs in a regime of extreme nonlinear fiber optics where positive and negative frequencies mix
164 citations
08 Feb 2019
TL;DR: In this article, an active nonlinear micro-ring resonator (MRR) was used as a high-quality micro-comb source and a passive high-Q MRR was used to slice the RF spectra modulated on the shaped comb.
Abstract: We demonstrate high-resolution photonic RF filters using an RF bandwidth scaling approach based on integrated Kerr optical micro-combs. By employing both an active nonlinear micro-ring resonator (MRR) as a high-quality micro-comb source and a passive high-Q MRR to slice the RF spectra modulated on the shaped comb, a large RF instantaneous bandwidth of 4.64 GHz and a high resolution of 117 MHz are achieved, together with a broad RF operation band covering 3.28–19.4 GHz (L to Ku bands) using thermal tuning. We achieve programmable RF transfer functions including binary-coded notch filters and RF equalizing filters with reconfigurable slopes. Our approach is an attractive solution for RF spectral shaping with high performance and flexibility.
151 citations
TL;DR: In this article, the discovery of ferromagnetic magnetism in a layered van der Waals semiconductor, VI3, is reported in which honeycomb vanadium layers are separated by an iodine-iodine van der Wals gap.
Abstract: 2D materials are promising candidates for next-generation electronic devices. In this regime, insulating 2D ferromagnets, which remain rare, are of special importance due to their potential for enabling new device architectures. Here the discovery of ferromagnetism is reported in a layered van der Waals semiconductor, VI3 , which is based on honeycomb vanadium layers separated by an iodine-iodine van der Waals gap. It has a BiI3 -type structure ( R 3 ¯ , No.148) at room temperature, and the experimental evidence suggests that it may undergo a subtle structural phase transition at 78 K. VI3 becomes ferromagnetic at 49 K, below which magneto-optical Kerr effect imaging clearly shows ferromagnetic domains, which can be manipulated by the applied external magnetic field. The optical bandgap determined by reflectance measurements is 0.6 eV, and the material is highly resistive.
147 citations
01 Mar 2019
TL;DR: In this article, the basic physics and the linear optical properties of carbon, carbon nanotube, and graphene have been introduced and discussed using the ultrafast nonlinear phenomena possessed by these 1D/2D materials: saturable absorption, electro-optic effect, and nonlinear Kerr effect.
Abstract: One- and two-dimensional forms of carbon, carbon nanotube, and graphene, and related 2D materials, have attracted great attention of researchers in many fields for their interesting and useful electrical, optical, chemical, and mechanical properties. In this tutorial, we will introduce the basic physics and the linear optical properties of these 1D/2D materials. We then focus on their nonlinear optical properties, saturable absorption, electro-optic effect, and nonlinear Kerr effect. We will also review and discuss a few key applications using the ultrafast nonlinear phenomena possessed by these 1D/2D materials: (1) short-pulse fiber lasers using saturable absorption, (2) electro-optic modulators, and (3) all-optical signal processing devices.
138 citations
TL;DR: In this article, an intrinsically tunable two-cavity magnon system that can achieve non-reciprocal light transmission, based on the magnon Kerr effect, was proposed.
Abstract: While nonreciprocal devices such as light isolators and circulators are becoming indispensable components in classical and quantum information processing, nonreciprocity in cavity magnon systems, which offer distinct advantages, still needs investigation. This study proposes an intrinsically tunable two-cavity magnon system that can achieve nonreciprocal light transmission, based on the magnon Kerr effect. By adjusting the external magnetic field, even one-way transmission can be obtained. These results point the way to microscale magnonic structures for potential applications in light diodes, on-chip light control, and optical communication.
80 citations
TL;DR: In this paper, a laser-written waveguide array with periodic variations along the waveguide axis was used to observe solitons in the bulk of a photonic Floquet topological insulator, where the nonlinearity arises from the optical Kerr effect of the ambient glass.
Abstract: Topological materials exhibit properties dictated by quantised invariants that make them robust against perturbations. This topological protection is a universal wave phenomenon that applies not only in the context of electrons in solid-state materials but also to photonic systems, ultracold atoms, mechanical systems, circuits, exciton-polaritons and beyond. However, the vast majority of research in these systems has focused on the linear domain, i.e., where inter-particle interactions do not play a role. Here, we experimentally observe solitons -- waves that propagate without changing shape as a result of nonlinearity -- in the bulk of a photonic Floquet topological insulator. These solitons exhibit fundamentally different behaviour than solitons in ordinary band gaps in that they execute cyclotron-like orbits that are associated with the topology of the lattice. Specifically, we employ a laser-written waveguide array with periodic variations along the waveguide axis that give rise to non-zero Floquet winding number, where the nonlinearity arises from the optical Kerr effect of the ambient glass. The effect described here is applicable to a range of bosonic systems due to its description by the focusing nonlinear Schrodinger equation, i.e., the Gross-Pitaevskii equation with attractive interactions.
79 citations
TL;DR: In this paper, the authors have presented the nonlinear medium such as passive non-linear medium like highly nonlinear fiber (HNLF) and active nonlinear Medium like SOA, and analyzed the performance of FWM when unequal channel spacing is considered.
Abstract:
This study has presented the nonlinear medium such as passive nonlinear medium like highly nonlinear fiber (HNLF) and active nonlinear medium like SOA. The FWM effects have ended up plainly huge at high optical power levels and have become even more meaningful when the capacity of the optical transmission line is increased, which has been reached through decreasing the channel separations. Also, anatomy has been done to analyze the performance of FWM when unequal channel spacing is considered. The outcomes indicate that when unequal channel spacing is used, the power levels of the beat frequency generated due to FWM effect in WDM system was increased to large values, so the performance of the wavelength division multiplexing (WDM) system is not enhanced, on the other hand when equal channel separations are used, and at the same bandwidth required to transmit 4 input channels the quality of receiving signal is greater than the system used unequal channel separation. This means that in the WDM system equal channels separation is more efficient than unequal channels separation-based SOA. The simulation is done using 4 channel wave division multiplexing signals at a rate of 10 Gb/s.
67 citations
TL;DR: In this article, the authors developed a theory for the magnon Kerr effect in a cavity magnonics system, consisting of magnons in a small yttrium iron garnet (YIG) sphere strongly coupled to cavity photons, and used it to study the bistability in this hybrid system.
Abstract: We develop a theory for the magnon Kerr effect in a cavity magnonics system, consisting of magnons in a small yttrium iron garnet (YIG) sphere strongly coupled to cavity photons, and use it to study the bistability in this hybrid system. To have a complete picture of the bistability phenomenon, we analyze two different cases in driving the cavity magnonics system, i.e., directly pumping the YIG sphere and the cavity, respectively. In both cases, the magnon frequency shifts due to the Kerr effect exhibit a similar bistable behavior but the corresponding critical powers are different. Moreover, we show how the bistability of the system can be demonstrated using the transmission spectrum of the cavity. Our results are valid in a wide parameter regime and generalize the theory of bistability in a cavity magnonics system.
65 citations
TL;DR: 2D RPPs are potential nanoscale all-optical modulators in the visible/near-infrared waveband for applications such as ultrafast information processing, optical data transmission and high-performance computing.
Abstract: Two-dimensional (2D) hybrid organic–inorganic Ruddlesden–Popper perovskites (RPPs) have been recently shown to exhibit large nonlinear optical properties due to the strong excitonic effects present...
56 citations
TL;DR: In this article, the optical Kerr nonlinearities of graphene/Si hybrid waveguides with enhanced self-phase modulation were investigated. And the authors achieved an enhanced nonlinear figure-of-merit (FOM) of 2.48 ± 0.25, which is four times larger than that of the Si waveguide.
Abstract: In this work, we experimentally study the optical Kerr nonlinearities of graphene/Si hybrid waveguides with enhanced self-phase modulation. In the case of CMOS compatible materials for nonlinear optical signal processing, Si and silicon nitride waveguides have been extensively investigated over the past decade. However, Si waveguides exhibit strong two-photon absorption (TPA) at telecommunication wavelengths, which leads to a significant reduction of the nonlinear figure-of-merit (FOM). In contrast, a silicon nitride based material system usually suppresses the TPA but simultaneously leads to the reduction of Kerr nonlinearity by one order of magnitude. Here, we introduce a graphene/Si hybrid waveguide, which maintains the optical properties and CMOS compatibility of Si waveguides, while enhancing the Kerr nonlinearity, by transferring over to the top of the waveguides. The graphene/Si waveguides are measured to have an enhanced nonlinear parameter of 510 W−1 m−1, compared with that of the Si waveguide of 150 W−1 m−1. An enhanced nonlinear FOM of 2.48 ± 0.25 has been achieved, which is four times larger than that of the Si waveguide of 0.6 ± 0.1. This work reveals the potential application of graphene/Si hybrid waveguides with high Kerr nonlinearity and FOM for nonlinear all-optical signal processing.
51 citations
TL;DR: It is demonstrated that a GaP film can generate sub–30-fs (full width at half maximum) transmission modulation of up to ~70% in the 600- to 1000-nm wavelength range, placing GaP as a promising ultrafast material for all-optical switching at modulation speeds ofup to 20 THz.
Abstract: Gallium phosphide (GaP) is one of the few available materials with strong optical nonlinearity and negligible losses in the visible (λ > 450 nm) and near-infrared regime. In this work, we demonstrate that a GaP film can generate sub–30-fs (full width at half maximum) transmission modulation of up to ~70% in the 600- to 1000-nm wavelength range. Nonlinear simulations using parameters measured by the Z -scan approach indicate that the transmission modulation arises from the optical Kerr effect and two-photon absorption. Because of the absence of linear absorption, no slower free-carrier contribution is detected. These findings place GaP as a promising ultrafast material for all-optical switching at modulation speeds of up to 20 THz.
TL;DR: In this paper, the optical Kerr effect is used to change the chemical potential of graphene-based plasmonic waveguides which are located in arms of a Mach-Zehnder interferometer.
TL;DR: In this paper, the authors explore optical activity in thin films and bulk of type-I and type-II Weyl semimetals (WSMs), and demonstrate the existence of a giant Kerr effect in both.
Abstract: We explore optical activity in thin films and bulk of type-I and type-II Weyl semimetals (WSMs), and demonstrate the existence of a giant Kerr effect in both. In time reversal symmetry broken WSM thin films, the polarization rotation is caused by the optical Hall conductivity including the anomalous Hall term. The Kerr angle is found to be $\ensuremath{\propto}Q/\ensuremath{\omega}$, with $Q$ and $\ensuremath{\omega}$ being the Weyl node separation and the optical frequency, respectively. In contrast, the optical activity in the bulk WSM is dominated by axion electrodynamics, which persists even in the Pauli-blocked regime of no optical transitions. In bulk WSMs, $Q$ acts analogously to the magnetization in magnetic materials, leading to a large polar Kerr effect (linear in $Q$), when light is incident on the WSM surface without Fermi arc states, and the Voigt effect (quadratic in $Q$), when light is incident on surface with Fermi arc states.
TL;DR: It is analytically demonstrated that the magnetoplasmonic response of dimer lattices is governed by a complex interplay of near- and far-field interactions, which enhances the polarizabilty of single dimers compared to that of isolated Ni nanodisks.
Abstract: We present a systematic study on the optical and magneto-optical properties of Ni/SiO2/Au dimer lattices. By considering the excitation of orthogonal dipoles in the Ni and Au nanodisks, we analytically demonstrate that the magnetoplasmonic response of dimer lattices is governed by a complex interplay of near- and far-field interactions. Near-field coupling between dipoles in Ni and low-loss Au enhances the polarizabilty of single dimers compared to that of isolated Ni nanodisks. Far-field diffractive coupling in periodic lattices of these two particle types enlarges the difference in effective polarizability further. This effect is explained by an inverse relationship between the damping of collective surface lattice resonances and the imaginary polarizability of individual scatterers. Optical reflectance measurements, magneto-optical Kerr effect spectra, and finite-difference time-domain simulations confirm the analytical results. Hybrid dimer arrays supporting intense plasmon excitations are a promising candidate for active magnetoplasmonic devices.
TL;DR: In this article, the authors reported the direct measurement of the nonlinear refractive index coefficient of liquid water by using the Z-scan method with broadband pulsed THz beam, which can be as large as 7×10-10 cm2/W in the THz frequency range and exceeds the values for the visible and NIR ranges by 6 orders of magnitude.
Abstract: The values of the nonlinear refractive index coefficient for various materials in the terahertz frequency range exceed the ones in both visible and NIR ranges by several orders of magnitude. This allows to create nonlinear switches, modulators, systems requiring lower control energies in the terahertz frequency range. We report the direct measurement of the nonlinear refractive index coefficient of liquid water by using the Z-scan method with broadband pulsed THz beam. Our experimental result shows that nonlinear refractive index coefficient in water is positive and can be as large as 7×10-10 cm2/W in the THz frequency range, which exceeds the values for the visible and NIR ranges by 6 orders of magnitude. To estimate n2, we use the theoretical model that takes into account ionic vibrational contribution to the third-order susceptibility. We show that the origins of the nonlinearity observed are the anharmonicity of molecular vibrations.
TL;DR: In this study, merging two photonic crystal-based structures, a new design for an all-optical 2-to-4 decoder has been proposed that can be qualified as a part of optical integrated circuits.
Abstract: In this study, merging two photonic crystal-based structures, a new design for an all-optical 2-to-4 decoder has been proposed. The switching operation is based on the Kerr effect and refractive index modification. The structure consists of one nonlinear ring resonator and three nonlinear cavities that have been modified for entering the slow-light regime in order to enhance coupling through waveguides. The maximum group index of 94 has been obtained for the proposed slow-light waveguides. With this approach, the maximum and minimum normalized output powers for logic 0 and 1 are 4% and 82%, respectively. The data transfer rate of the decoder is 220 GHz, and the size of the structure is 24×9.5 μm2. The maximum insertion loss and cross talk are −7.45 dB and −16.38 dB, respectively. Considering the above characteristics, the proposed decoder can be qualified as a part of optical integrated circuits.
TL;DR: In this paper, a terahertz all-optical tunable filter comprised of arrays of graphene microdisks deposited on a dielectric substrate is proposed, which exhibits a wide-angle response and also due to the symmetric structure is polarization-insensitive.
TL;DR: In this paper, an effective way of photon controlling and finding the photon-blockade effect in the hybrid optomagnonic microcavity was investigated, where the magnons and photons in both transverse electric and transverse magnetic modes can be converted into the supermode photons under the Kerr effect.
Abstract: Controlling the interaction between the spin wave and the electromagnetic field is an important issue of optoelectronics. The effect of photon blockade is to indicate the interaction that prevents multiple photons from entering the cavity simultaneously, which is the pivotal effect to achieve the photons at the quantum level. Here in this study, we investigate an effective way of photon controlling and find the photon-blockade effect in the hybrid optomagnonic microcavity. Specifically, we show that the magnons and photons in both transverse electric and transverse magnetic modes can be converted into the supermode photons under the Kerr effect. Also the correlation function of the photons is analytically studied, which shows the asymmetry behavior for the two different supermodes. This proposed system opens up a route to control the optical mode in hybrid microresonators, which are important for advanced quantum technologies.
TL;DR: In this article, simultaneous measurements of the anomalous Hall effect (AHE) and the magneto-optical Kerr effect (MOKE) through two magnetic phase transitions are compared, and the results point to a difference between the bulk and surface magnetic properties of Mn3Sn.
Abstract: In the non-collinear antiferromagnet Mn3Sn, we compare simultaneous measurements of the anomalous Hall effect (AHE) and the magneto-optical Kerr effect (MOKE) through two magnetic phase transitions: the high-temperature paramagnetic/antiferromagnetic (AF) phase transition at the Neel temperature (TN ≈ 420 K) and a lower-temperature incommensurate magnetic ordering at T1 ≈ 270 K. While both the AHE and MOKE are sensitive to the same underlying symmetries of the AF non-collinear spin order, we find that the transition temperatures measured by these two techniques unexpectedly differ by approximately 10 K. Moreover, the applied magnetic field at which the AF order reverses is significantly larger when measured by MOKE than when measured by AHE. These results point to a difference between the bulk and surface magnetic properties of Mn3Sn.
TL;DR: Findings suggest that BPQD-based novel nonlinear photonics devices could be further developed in the applications of next generation high-speed optical communication.
Abstract: As a unique two-dimensional material, few-layered black phosphorus (BP) nanosheets have shown promising applications in electronics and optoelectronics. Black phosphorus quantum dots (BPQDs) have attracted attention due to the unique properties of BP combined with the edge effects. In this paper, we report on the all-optical application of BPQD based on its nonlinear Kerr effect. BPQDs were synthesized using a liquid exfoliation method combined with probe sonication and bath sonication. BPQD deposited on the microfiber as an optical device was demonstrated as the Kerr switcher with extinction ratio of 20 dB and four-wave mixing based wavelength converter with -40 dB conversion efficiency. These findings suggest that BPQD-based novel nonlinear photonics devices could be further developed in the applications of next generation high-speed optical communication.
TL;DR: In this paper, the influence of the DC Kerr effect in silicon photonic Mach-Zehnder modulators (MZMs) and the ability to optimize the combined effects of plasma dispersion and DC Kerr to achieve linear transfer characteristics was demonstrated.
Abstract: We experimentally demonstrate the influence of the DC Kerr effect in silicon photonic Mach-Zehnder modulators (MZMs) and the ability to optimize the combined effects of plasma-dispersion and DC Kerr to achieve linear transfer characteristics and thus demonstrate suitability for microwave photonic links and digital modulation formats such as multilevel pulse amplitude modulation. PN and PiN doped modulators were fabricated through AIM Photonics. Intermodulation distortion products are demonstrated to have reverse bias and MZM bias dependencies advantageous for highly linear operation. The spurious-free dynamic range, gain, and noise figure are optimized by choice of phase modulator reverse bias and MZM bias point yielding analog links with spurious-free dynamic ranges greater than 100 dB·Hz2/3. The silicon modulators demonstrate link spurious-free dynamic ranges on par with a commercial lithium niobate modulator. Furthermore, we show that simulations including the DC Kerr effect can reliably predict device performance although direct prediction of analog link metrics remains challenging, and final tuning of the device operating conditions is required to achieve optimum performance.
20 Jun 2019
TL;DR: In this paper, the authors presented a novel in situ method to measure the nonlinear refractive index and absorption coefficient in micro-resonators and provided a powerful new approach for characterization of micro-onors and optical materials and pave the way for new opportunities in the area.
Abstract: Microresonators offer an attractive combination of high quality factors and small optical mode volume. They have emerged as a unique platform for the study of fundamental physics and for applications ranging from exquisite sensors to miniature optical combs. Characterizing the linear and nonlinear properties of a microresonator is the first step toward new applications. Here, we present a novel in situ method to measure the nonlinear refractive index and absorption coefficient in microresonators. Laser-scanned transmission spectra are fitted by a comprehensive theoretical model that includes the thermo-optic effect, Kerr effect, and back-coupling of counter-propagating modes. The effectiveness of our technique is demonstrated by evaluating the nonlinear indices and optical absorption of silica and chalcogenide (As2S3) microspheres at 1.55 μm. Significantly, our method also quantifies important parameters including the quality factor, thermal relaxation time, and back-coupling coefficient at the same time. Our findings provide a powerful new approach for characterization of microresonators and optical materials and pave the way for new opportunities in the area.
TL;DR: 3D topological Dirac/Weyl semimetals possess bulk structural advantage not found in the strictly two-dimensional graphene, greater design flexibility and improved ease-of-fabrication in terms of photonic and optoelectronic device applications can be achieved.
Abstract: We study the nonlinear optical response generated by the massless Dirac quasiparticles residing around the topologically-protected Dirac/Weyl nodal points in three-dimensional (3D) topological semimetals. Analytical expressions of third-order interband nonlinear optical conductivities are obtained based on a quantum mechanical formalism which couples 3D Dirac fermions with multiple photons. Our results reveal that the massless Dirac fermions in three dimensions retains strong optical nonlinearity in terahertz frequency regime similar to the case of the two-dimensional Dirac fermions in graphene. At room temperature, the Kerr nonlinear refractive index and the harmonic generation susceptibility are found to be n2 = 10−11 ∼ 10−8 m2W−1 and χ(3) = 10−14 ∼ 10−8 m2V−2, respectively, in the few terahertz frequency regimes, which is comparable to graphene and orders of magnitudes stronger than many nonlinear crystals. Importantly, because 3D topological Dirac/Weyl semimetals possess bulk structural advantage not found in the strictly two-dimensional graphene, greater design flexibility and improved ease-of-fabrication in terms of photonic and optoelectronic device applications can be achieved. Our finding reveals the potential of 3D topological semimetals as a viable alternative to graphene for nonlinear optics applications.
TL;DR: In this article, simultaneous measurements of the anomalous Hall effect (AHE) and the magneto-optical Kerr effect (MOKE) through two magnetic phase transitions were conducted for the non-collinear antiferromagnet Mn$_3$Sn.
Abstract: In the non-collinear antiferromagnet Mn$_3$Sn, we compare simultaneous measurements of the anomalous Hall effect (AHE) and the magneto-optical Kerr effect (MOKE) through two magnetic phase transitions: the high-temperature paramagnetic/antiferromagnetic phase transition at the N\'eel temperature ($T_N \approx$420~K), and a lower-temperature incommensurate magnetic ordering at $T_1 \approx$270~K. While both the AHE and MOKE are sensitive to the same underlying symmetries of the antiferromagnetic non-collinear spin order, we find that the transition temperatures measured by these two techniques unexpectedly differ by approximately 10~K. Moreover, the applied magnetic field at which the antiferromagnetic order reverses is significantly larger when measured by MOKE than when measured by AHE. These results point to a difference between the bulk and surface magnetic properties of Mn$_3$Sn.
TL;DR: In this paper, the transverse magneto-optical Kerr effect (TMOKE) in magnetite-based magnetoplasmonic crystals is studied experimentally and theoretically.
Abstract: The transverse magneto-optical Kerr effect (TMOKE) in magnetite-based magnetoplasmonic crystals is studied experimentally and theoretically. We analyze angle-resolved TMOKE spectra from two types of structures where noble metallic stripes are incorporated inside a thin magnetite film or located on top of a homogeneous film. A multiple-wide-band enhancement of the TMOKE signal in transmission is demonstrated. The complex dielectric permittivity and gyration are experimentally determined using the ellipsometry technique as well as Faraday rotation and ellipticity measurements. The obtained parameters are used in rigorous coupled-wave analysis (RCWA) calculations for studying the optical resonances. Our RCWA calculations of transmittance and TMOKE are in good agreement with the experimental data. The role of guiding and plasmonic modes in the TMOKE enhancement is revealed. We demonstrate that the TMOKE provides rich information about the studied optical resonances.
TL;DR: In this paper, the authors demonstrate Kerr-frequency-comb generation with nanofabricated Fabry-Perot resonators, which are formed with photonic-crystal-reflector (PCR) mirrors.
Abstract: We demonstrate Kerr-frequency-comb generation with nanofabricated Fabry–Perot resonators, which are formed with photonic-crystal-reflector (PCR) mirrors. The PCR group-velocity dispersion (GVD) is ...
TL;DR: In this paper, the authors demonstrate a combined frequency and time domain investigation of injection-locked, constriction-based spin Hall nano-oscillators by Brillouin light scattering (BLS) and the time-resolved magneto-optical Kerr effect (TR-MOKE).
Abstract: We demonstrate a combined frequency and time domain investigation of injection-locked, constriction-based spin Hall nano-oscillators by Brillouin light scattering (BLS) and the time-resolved magneto-optical Kerr effect (TR-MOKE). This was achieved by applying an ac current in the GHz regime in addition to the dc current which drives auto-oscillations in the constriction. In the frequency domain, we analyze the width of the locking range, the increase in intensity, and the reduction in the linewidth as a function of the applied direct current. Then, we show that the injection locking of the auto-oscillation allows for its investigation by TR-MOKE measurements, a stroboscopic technique that relies on a phase stable excitation, in this case given by the synchronisation to the microwave current. Field sweeps at different dc currents clearly demonstrate the impact of the spin current on the Kerr amplitude. Two-dimensional TR-MOKE and BLS maps show a strong localization of the auto-oscillation within the constriction, independent of the external locking.
TL;DR: The propagation properties of the circular Pearcey Gaussian waves in Kerr medium are introduced and the distinctive stepwise focusing of the imaginary part of the CPG waves which can be applied to wave modulation is introduced.
Abstract: We introduce the propagation properties of the circular Pearcey Gaussian (CPG) waves in Kerr medium for the first time. The breathers-like structure and breathers-like groups structure (filamentions) of CPG waves will form due to the interaction between the linear waves and the nonlinear medium. The focusing characteristics in Kerr medium can be adjusted by the deviation factor and the initial input power of the CPG waves. By choosing appropriate input power, the imaginary part of the CPG waves can split into some wavelets during the propagation. It is worth noting that the distinctive stepwise focusing of the imaginary part of the CPG waves which can be applied to wave modulation. Furthermore, the numerical experiment results show good agreement with the numerical simulation results.
TL;DR: In this article, the authors developed a theory for the magnon Kerr effect in a cavity magnonics system, consisting of magnons in a small yttrium iron garnet (YIG) sphere strongly coupled to cavity photons, and used it to study the bistability in this hybrid system.
Abstract: We develop a theory for the magnon Kerr effect in a cavity magnonics system, consisting of magnons in a small yttrium iron garnet (YIG) sphere strongly coupled to cavity photons, and use it to study the bistability in this hybrid system. To have a complete picture of the bistability phenomenon, we analyze two different cases in driving the cavity magnonics system, i.e., directly pumping the YIG sphere and the cavity, respectively. In both cases, the magnon frequency shifts due to the Kerr effect exhibit a similar bistable behavior but the corresponding critical powers are different. Moreover, we show how the bistability of the system can be demonstrated using the transmission spectrum of the cavity. Our results are valid in a wide parameter regime and generalize the theory of bistability in a cavity magnonics system.
TL;DR: In this paper, Co2FeAl (CFA) thin films of 50nm thickness have been grown on MgO (0,0,1) single crystal substrates at room temperature with and without post-annealing (PA) at 300 and 400°C using dual ion-beam sputtering technique.