Enhancement Of Magneto-optical Effect Research Articles

Numerical finite-difference time-domain calculation for extreme enhancement of magneto-optical effect at ultraviolet wavelength using Ni-subwavelength grating on SiO2/Ni structure

Numerical finite-difference time-domain calculation for extreme enhancement of magneto-optical effect at ultraviolet wavelength using Ni-subwavelength grating on SiO2/Ni structure

Enhancement of magneto-optical effects by a single 1D all dielectric resonant grating

We demonstrate theoretically the enhancement of the four first-order magneto-optical effects using an all-dielectric 1D resonant grating. The modeled structure was designed for the Faraday effect at normal incidence at a wavelength of 1.55 µm for which the calculated improvement is shown to be one hundred times the off-resonance values. At 1° incidence, polar and longitudinal Kerr effects were also improved, showing polarization rotations up to 14°. For the same incidence conditions, transverse magneto optical Kerr effect was also improved, leading to a reflectance difference of 12% for a reflectance intensity of 40%. These results are interesting for the development of magnetic-field sensors capable of detecting of several components of the field.

Magneto-optical response in bimetallic metamaterials

Abstract We demonstrate resonant Faraday polarization rotation in plasmonic arrays of bimetallic nano-ring resonators consisting of Au and Ni sections. This metamaterial design allows the optimization of the trade-off between the enhancement of magneto-optical effects and plasmonic dissipation. Nickel sections corresponding to as little as ~6% of the total surface of the metamaterial result in magneto-optically induced polarization rotation equal to that of a continuous nickel film. Such bimetallic metamaterials can be used in compact magnetic sensors, active plasmonic components, and integrated photonic circuits.

Enhancement of magneto-optical effect via the evanescent wave and its figure of merit

We investigate the enhancement of the magneto-optical (MO) effect via the evanescent wave in MO structures composed of GdFe thin layers and two dielectrics. The MO Kerr rotation and the figure of merit (FOM) among the Kretschmann, Otto and direct-irradiation configurations are compared. The data obtained by experiment and calculation both show that the standing evanescent wave in the metal layer realized in the former two configurations enhances the MO Kerr rotation and FOM. Furthermore, the Kretschmann configuration appears to be superior to the Otto configuration in terms of the efficiency of MO Kerr enhancement.

Enhancement of magneto-optical effects in magnetic nanoparticles near gold-dielectric surfaces

We report enhanced magneto-optical Kerr rotation in the layer systems of a magnetic granular film coated by uniform gold and dielectric films. The Kerr rotation spectra measured from 1.2 to 5 eV show a peak at about 2.7 eV, not present in either uncoated magnetic particle films. It was shown that the polar magneto-optical Kerr signal is about five times higher than that obtained for CoFe-MgO granular films in similar conditions. The physical nature of the magneto-optical effect enhancement in three layers (magnetic/noble/dielectric films) is related to the excitation of surface plasmons and their fast propagation on the interface of a complex three-layer structure. The Kerr rotation enhancement corresponds to intrinsic electronic transitions in the CoFe nanogranules due to the spectral overlap of these transitions with propagating surface plasmons.

Plasmon resonance enhancement of magneto-optic effects in garnets

Enhancement of magneto-optic effects by strong electric fields induced by plasmon resonances in metallic nanoparticles placed on (or embedded into) garnets is discussed. Theoretical and computational results on excitation of plasmon resonances in such particles are reported and compared to available experimental data.

Magneto-optical studies of Cd1−x−yMnxCoyTe

We have investigated the optical absorption and magneto-optical properties of quaternary Cd1-x−yMnxCoyTe crystals (x=0.37, 0≤y≤0.009) grown by the vertical Bridgman method. The presence of Co showed a significant enhancement of magneto-optical effects as compared to ternary Cd0.63Mn0.37Te system with the same Mn content. Four features were observed in magnetic circular dichroism (MCD) spectra of these alloys, located near 1.37, 1.45, 1.82, and 2.13 eV. We present detailed temperature dependences of the position and intensity of these MCD features, and we discuss their possible origins.

Control of Diffracted Magneto-Optical Enhancement in Ni Gratings

The so-called diffracted magneto-optical (MO) effects, in which the MO responses of diffracted beams are measured in the off-specular geometry, have been utilized to change the amplitude and the sign of MO signals. An enhancement of MO effect of the first-order diffraction was found. In this paper, the rigorous coupled-wave analysis implemented as Airy-like internal reflection series was developed to simulate the diffracted longitudinal MO Kerr effect. We demonstrate that the enhancement of the MO effect is controllable for a certain diffraction order by adjusting the geometrical parameters of Ni gratings. Furthermore, it is believed that the absolute magnitude and the MO enhancement can be more effectively tuned by designing the grating profile and carefully selecting the gyrotropic materials.

Magnetooptical effects in metal-dielectric plasmonic systems

Enhancement of magneto-optical effects in two-layer systems composed of perforated metal and magnetized dielectric films is theoretically predicted. The transmission and magneto-optical effect spectra of such systems are calculated and the conditions are determined that make it possible to enhance the Faraday effect by an order of magnitude in comparison with homogeneous magnetized films.

Enhancement of Magneto Optic Effect in Optical Isolator with GaInAsP Guiding Layer by Selective Oxidation of AlInAs

A selectively oxidized AlInAs layer with low refractive index can enhance the magneto optic effect and improve the characteristics of optical nonreciprocal devices. We successfully fabricated an optical waveguide with an AlInAs oxide lower cladding layer. The refractive index of the AlInAs oxide was determined to be 2.45 at λ=1.55 µm. The optical nonreciprocal phase shift of this waveguide was more than twelvefold than that of the magneto optic waveguide with an InP cladding layer.

Bismuth-induced enhancement of magneto-optical effects in iron garnets: A theoretical analysis

A semiquantitative model of circular magneto-optical effects in iron garnets is constructed within the concept of charge-transfer transitions and the existing qualitative notions. In the framework of the proposed model, the drastic enhancement of circular magneto-optical effects in R3Fe5O12 iron garnets containing impurities of Bi3+ or Pb2+ ions is explained by the increase in the oxygen contribution to the spin-orbit coupling constant of the (FeO6)9− and (FeO4)5− complexes (the main magneto-optically active centers in iron garnets). This increase is associated with the covalent admixture of the Bi3+ (or Pb2+) 6p orbitals (with a giant one-electron spin-orbit coupling constant) to the oxygen 2p orbitals. The influence of the substitution does not reduce to an enhancement of the oxygen spin-orbit interaction alone but also leads to the appearance of the effective anisotropic tensor contributions to the spin-orbit interaction and circular magneto-optical effects. These contributions to the magneto-optical effects in garnets are estimated. The influence of an inhomogeneous bismuth distribution on the magneto-optical effects in Y3−xBixFe5O12 garnets is investigated using computer simulation. Analysis of the available experimental data on the magneto-optical effects in garnets confirms the validity of the theoretical model proposed.

Enhancement of magneto-optical effect in a GaAs : MnAs hybrid nanostructure sandwiched by GaAs/AlAs distributed Bragg reflectors: epitaxial semiconductor-based magneto-photonic crystal

It is shown that magneto-optical effect can be controllably enhanced in a molecular beam epitaxy (MBE) grown semiconductor-based multilayer structure consisting of a magnetic layer and GaAs/AlAs distributed Bragg reflectors (DBR), that is a one-dimensional semiconductor-based magneto-photonic crystal. Here, the magnetic layer is GaAs containing MnAs nanoscale clusters (GaAs : MnAs), which can be formed by annealing (GaMn)As alloys at 500–750°C. Structural and magneto-optical properties of GaAs : MnAs are presented and its dielectric functions are derived. It is shown that DBR/GaAs : MnAs/DBR structures were successfully grown by MBE and their magneto-optical effect is enhanced due to the localization of light at the Bragg wavelength. Comparison with theoretical calculations of the magneto-optical properties and device potentials are also discussed.

Selective oxidation for enhancement of magneto-optic effect in optical isolator with semiconductor guiding layer

Selective oxidation of an AlInAs layer grown on an InP substrate is studied with a view to enhancing the magneto-optic effect in an optical isolator with a semiconductor guiding layer. The isolator operates with a nonreciprocal phase shift in a magneto-optic waveguide. The waveguide with an AlInAs oxide cladding layer miniaturises the nonreciprocal phase shifter to several hundreds of microns.

Enhancement of magneto-optic effects via large atomic coherence in optically dense media

We utilize the generation of large atomic coherence to enhance the resonant nonlinear magneto-optic effect by several orders of magnitude, thereby eliminating power broadening and improving the fundamental signal-to-noise ratio. A proof-of-principle experiment is carried out in a dense vapor of Rb atoms. Detailed numerical calculations are in good agreement with the experimental results. Applications such as optical magnetometry or the search for violations of parity and time reversal symmetry are feasible.

Enhancement of Magneto-Optical Effects through Polarized Pt and Pd in TbFeCo/(Pt,Pd) Multilayers

Enhancement of Magneto-optical Effects through Polarized Pt and Pd in TbFeCo/(Pt, Pd) Multilayers

Enhancement of Magneto-optical Effects through NdCo and Pt in TbFeCo

Magneto-optical effects of TbFeCo/NdCo and TbFeCo/Pt multilayer films and NdTbFeCo alloy films prepared by sputter deposition are discussed in conjunction with the multilayer structure and the composition. The contribution to the polar Kerr spectra due to NdCo and Pt layers is significantly found at ultra- violet photon energies for both cases. In TbFeCo/NdCo multilayers, it is found that the enhancements of Kerr rotation θK and ellipticity ηK increase with NdCo layer thickness and become saturated at tNdCo = 15 Å for the case of tTbFeCo = 30 Å. In TbFeCo/Pt multilayer, the θK and ηK are also enhanced with Pt layer thickness and become saturated at tpt= 12 Å.