Alexander I. Musorin

Faraday rotation induced by Bloch surface waves in magnetophotonic crystals (Conference Presentation)

The magnetooptical control of light implies different directions of polarization plane rotation, linear-to-circular and other polarization transformations. These opportunities can be opened using polarization-sensitive resonances, for example, Bloch surface waves (BSWs) and waveguide modes (WGMs) in magnetophotonic crystals (MPCs) [1]. Magneto-optical phenomena, such as Faraday effect, can be significantly increased near spectrally narrow optical resonances [2]. In this case, the Faraday rotation angle is determined both by the magnetic properties of the material and by the Q-factor of the resonances, which define their spectral width. The resonance of the BSW is shown to be extremely narrow. The proper choice of the MPC parameters gives the ways to observe the s-polarized BSW and p-polarized WGM of the MPC in the same spectral region. Here, we experimentally demonstrate how a fundamental property of magneto-optical effects to couple two linearly polarized modes allows one to control and modify the values of Faraday rotation angles. The interplay of the BSW and WGM results in an enhancement of the Faraday rotation angle, change of lineshape of Faraday rotation spectra and direction of the polarization rotation. Reflectance spectra of the one-dimensional magnetophotonic crystal and the corresponding Faraday rotation spectra were experimentally measured using the Kretschmann attenuated total internal reflection configuration and numerically calculated using the transfer matrix approach [3]. The studied magnetophotonic crystal sample consists of 15 alternating layers of fused quartz and Bi-substituted yttrium-iron-garnet on a sGGG substrate. The BSW excitation corresponds to a narrow resonance in the reflectance spectra of the s-polarized light. Wide dips in the reflectance spectra of p-polarized light correspond to the WGM resonances. As the incident angle increases, both the resonances shift to short wavelengths, but the WGM resonance shifts faster; thus, the spectral distance between the BSW and WGM resonances decreases. The spectral dependence of the Faraday rotation angle of s-polarized light has a feature coinciding in the BSW wavelength and caused by the BSW excitation. The feature in the Faraday rotation spectrum has a Fano resonance shape and changes from an asymmetric shape to a symmetric one, while the incident angle increases and the BSW and the WGM resonances approach each other. This behavior is observed both in the experiment and calculations. Thus, it can be argued that the spectral dependence of the Faraday rotation angle depends not only on the BSW resonance in the structure but also on the coupling of the BSW with the WGM mode that is not excited in the s-polarization of the incident light. Besides, the Faraday rotation changes direction while BSW and the WGM resonances spectral position approach each other that makes these resonance in MPCs promising for the future photonics devices. [1] M. N. Romodina, I. V. Soboleva, A. I. Musorin, Y. Nakamura, M. Inoue, A. A. [2] M. Inoue, M. Levy, A.V. Baryshev, Magnetophotonics: From Theory to Appli- cations, Springer Series in Materials Science, 2013. [3] D.W. Berreman, J. Opt. Soc. Am. 62, 502–510 (1972).

Enhanced magneto-optical effects in dielectric Mie-resonant metasurfaces

The concept of the rapidly developing area of high-index resonant meta-optics is extended to the field of mag- netically active materials. We numerically analyze magneto-optical response of hybrid nickel-silicon (Ni/Si) nanoantennas in comparison with an all-dielectric analog based on the bismuth substituted iron yttrium garnet- silicon (Bi:YIG/Si) nanoantennas. The results demonstrate the multifold enhancement of the magneto-optical effects due to the Mie-type resonances excitation in the structure. To further optimize the magneto-optical re- sponse and achieve a significant enhancement of the effect, the metasurfaces composed of Ni/Si nanoantennas of the different shape and configuration are numerically simulated. The magneto-optical effects can be significantly enhanced by means of the specific design of these hybrid metasurfaces.

Magneto-optical effects from nanoparticles enhanced by Mie resonances

Control of light by an external magnetic field is one of the important methods for modulation of its intensity and polarization. Magneto-optical effects at the nanoscale are usually observed in nanostructured hybrid materials or magnetoplasmonic crystals. In this work, we combine the advantages of all-dielectric resonant nanostructures and magnetic materials for creating compact active magneto-optical metadevices. High-index nanostructures offer novel opportunities for controlling light at the nanoscale based on a strong localization of both electric and magnetic fields in such structures near the corresponding Mie resonance [1]. This fact makes them similar to plasmonic nanostructures with clear advantage that all-dielectric meta-optics structures composed of nanoparticles with high refractive index can overcome this limit and initiate a new platform for nanophotonic metadevices [2]. As the important next step in this field, we consider a control of optical properties by an applied magnetic field, known to be an effective tool for many plasmonic structures [3, 4].

Bloch-surface-waves-induced fano resonance in magneto-optical response of magnetophotonic crystals

Magnetophotonic crystals (MPCs) support Bloch surface waves (BSWs) and waveguided modes (WGMs) propagation. The influence of the BSW on the Faraday effect in the one-dimensional MPCs is studied. The technique of measuring the angle of Faraday rotation in the MPCs in attenuated total internal reflection scheme in Kretschmann configuration is discussed. The spectra of Faraday rotation demonstrate a Fano-shaped resonance near the spectral-angular position of the BSW resonance both for s- and p-polarized incident light. The presence of the feature in the spectrum of p-polarized light can be explained by the Faraday rotation effect and subsequent BSW excitation mutually enhancing each other.

The correlation between magneto-optical response and magnetic dipole resonance excitation in subwavelength silicon-nickel nanogratings

The advantages of gyrotopic materials are combined with the field of high-index metamaterials. The enhancement of the magneto-optical response in the spectral vicinity of the magnetic dipole resonance of a dielectric silicon nanodisks is numerically shown.

Ultrafast dynamics of Faraday rotation in thin films

Femtosecond Faraday rotation evolution and a propagation of a femtosecond pulse through a thin magnetic films is calculated and measured.

Polarization-sensitive correlation spectroscopy of Faraday-effect femtosecond dynamics

Femtosecond dynamics of the Faraday effect is experimentally studied in thin magnetic films by polarization-sensitive correlation spectroscopy.