Magnetophotonic intensity effects in hybrid metal-dielectric structures

Abstract

The magneto-optical properties of a hybrid metal-dielectric structure consisting of a one-dimensional gold grating on top of a magnetic waveguide layer are studied experimentally and theoretically. It is demonstrated that a magnetic field applied in the longitudinal configuration (in the plane of the magnetic film and perpendicular to the slits in the gold grating) to the metal-dielectric structure modifies the field distribution of the optical modes and thus changes the mode excitation conditions. In the optical far field, this manifests in the alteration of the optical transmittance or reflectance when the structure becomes magnetized. This magneto-optical effect is shown to represent a novel class of effects related to the magnetic-field-induced modification of the Bloch modes of the periodic hybrid structure. That is why we define this effect as "longitudinal magnetophotonic intensity effect" (LMPIE). The LMPIE has two contributions, odd and even in magnetization. While the even LMPIE is maximal for the light polarized perpendicular to the grating slits (TM) and minimal for the orthogonal polarization (TE), the odd LMPIE takes maximum values at some intermediate polarization and vanishes for pure TM and TE polarizations. Two principal modes of the magnetic layer-TM and TE-acquire in the longitudinal magnetic field additional field components and thus turn into quasi-TM and quasi-TE modes, respectively. The largest LMPIE is observed for excitation of the antisymmetrical quasi-TE mode by TM-polarized light. The value of the LMPIE measured for the plasmonic structure with a magnetic film of Bi 2 Dy 1 Fe 4 Ga 1 O 12 composition is about 1% for the even effect and 2% for the odd one. However, the plasmonic structure with a magnetic film with a higher concentration of bismuth (Bi 2.97 Er 0.03 Fe 4 Al 0.5 Ga 0.5 O 12) gives significantly larger LMPIE: even LMPIE reaches 24% and odd LMPIE is 9%. Enhancement of the magneto-optical figure of merit (defined as the ratio of the specific Faraday angle of a magnetic film to its absorption coefficient) of the magnetic films potentially causes the even LMPIE to exceed 100% as is predicted by calculations. Thus, the nanostructured material described here may be considered as an ultrafast magnetophotonic light valve.

Terahertz dynamics of lattice vibrations in Au/CdTe plasmonic crystals: Photoinduced segregation of Te and enhancement of optical response

“…Based on these principles, surface plasmon resonant sensors for the detection of chemical and biological species are developed [3]. In addition, one can use an external stimulus such as optical excitation [4][5][6][7][8], acoustic waves [9][10][11][12] and external magnetic fields [13][14][15][16] in order to influence the dielectric function of metal and/or dielectric and subsequently to control the SPP propagation constant. Therefore, SPPs are well suited for applications in optoelectronic devices where high sensitivities * lars.kreilkamp@tu-dortmund.de and efficient optical excitation at the nanoscale are essential [8].…”

Local probing of magnetic films by optical excitation of magnetostatic waves

“…For example, nanostructuring of the layer of magnetic materials leads to the emergence of new approaches in spintronics utilizing magnetic vortices and skyrmions [3][4][5]. On the other hand, periodic structures of perforated metallic and dielectric layers known as magnetoplasmon crystals [6][7][8][9][10][11] exhibit new optical properties accompanied by the considerable enhancement of magnetooptical effects under the condition of homogeneity of magnetic parameters of each magnetic layer of the structure. In both cases, functionality of magnetic materials is largely determined and limited by their local magnetic properties including magnetization and magnetic anisotropy constants.…”

Tunable Optical Nanocavity of Iron-garnet with a Buried Metal Layer

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