I.L. Lyubchanskii

Magnetic photonic crystals

In this paper we outline a new direction in the area of photonic crystals (PCs), or photonic band gap materials, i.e. one-, two-, or three-dimensional superstructures with periods that are comparable with the wavelengths of electromagnetic radiation. The main (and principal) characteristic of this new class of PCs is the presence of magnetically ordered components (or external magnetic field). The linear and nonlinear optical properties of such magnetic PCs are discussed.

One-dimensional bigyrotropic magnetic photonic crystals

Electromagnetic wave propagation in a one-dimensional magnetic photonic crystal (MPC) made of bigyrotropic magnetic yttrium–iron garnet and nonmagnetic gadolinium–gallium garnet is theoretically investigated using the 4×4 transfer matrix method. Band gaps in the electromagnetic spectrum are numerically obtained and appear to depend on the helicity and direction of light propagation through the MPC.

One-dimensional photonic crystal with a complex defect containing an ultrathin superconducting sublayer

The influence of the variation in the incidence angle on the photonic band gap spectra of a one-dimensional dielectric photonic crystal with a complex defect layer, consisting of ultrathin superconducting and dielectric sublayers, was theoretically investigated. The behavior of the defect modes with different polarizations as a function of the incidence angle variation is studied numerically for different thicknesses of the superconducting sublayer. The pronounced contrast in behavior of TE- and TM-polarized modes was demonstrated. The intensity of the TE-polarized defect mode decreases with increasing incidence angle, whereas the intensity of the TM-polarized defect mode increases. The increase in the superconducting defect sublayer thickness leads to a shift in the defect mode of TM-polarization to higher frequencies.

Second-harmonic generation from realistic film-substrate interfaces: The effects of strain

The optical second-harmonic generation from a thin crystalline film on a substrate is theoretically investigated for both s and p polarized incident light. The contributions of lattice misfit strain as well as of misfit dislocation strain to the second-order nonlinear optical susceptibility are described using a nonlinear photoelastic tensor and can be separated by a polarization analysis of the scattered light at the second harmonic frequency. For the s(v)!s(2v) and p(v)!s(2v) scattering geometries, the nonlinear optical signal will be determined by dislocation strain only, whereas for the s(v)! p(2v) and p(v)! p(2v) geometries both lattice misfit strain and misfit dislocation strain will contribute.

Goos-Hänchen effect and bending of spin wave beams in thin magnetic films

For magnon spintronic applications, the detailed knowledge of spin wave (SW) beam dispersion, transmission (reflection) of SWs passing through (reflected from) interfaces, or borders or the scattering of SWs by inhomogeneities is crucial. These wave properties are decisive factors on the usefulness of a particular device. Here, we demonstrate, using micromagnetic simulations supported by an analytical model, that the Goos-Hanchen (GH) shift exists for SW reflecting from thin film edge and that with the effect becomes observable. We show that this effect will exist for a broad range of frequencies in the dipole-exchange range, with the magnetization degree of pinning at the film edge as the crucial parameter, whatever its nature. Moreover, we have also found that the GH effect can be accompanied or even dominating by a bending of the SW beam due to the inhomogeneity of the internal magnetic field. This inhomogeneity, created by demagnetizing field taking place at the film edge, causes gradual change of SWs refractive index. The refraction of the SW beams by the non-uniformity of the magnetic field enables the exploration of graded index magnonics and metamaterial properties for the transmission and processing of information at nanoscale.

Photonic-magnonic crystals: Multifunctional periodic structures for magnonic and photonic applications

We investigate the properties of a photonic-magnonic crystal, a complex multifunctional one-dimensional structure with magnonic and photonic band gaps in the GHz and PHz frequency ranges for spin waves and light, respectively. The system consists of periodically distributed dielectric magnetic slabs of yttrium iron garnet and nonmagnetic spacers with an internal structure of alternating TiO2 and SiO2 layers which form finite-size dielectric photonic crystals. We show that the spin-wave coupling between the magnetic layers, and thus the formation of the magnonic band structure, necessitates a nonzero in-plane component of the spin-wave wave vector. A more complex structure perceived by light is evidenced by the photonic miniband structure and the transmission spectra in which we have observed transmission peaks related to the repetition of the magnetic slabs in the frequency ranges corresponding to the photonic band gaps of the TiO2/SiO2 stack. Moreover, we show that these modes split to very high sharp (a...

Nonlinear magneto-optical diffraction from periodic domain structures in magnetic films

The nonlinear optical diffraction in magnetic films with a laminar domain structure and Bloch-type domain walls is investigated for both s and p polarization of incident light. It is shown that the contribution of magnetic domains and domain walls to the nonlinear diffraction can be separated by a polarization analysis of the scattered light.

Optical bistability in one-dimensional magnetic photonic crystal with two defect layers

One-dimensional magnetic photonic crystal with two magnetic defect layers is theoretically studied. The dependence of defect modes inside photonic band gap on the distance between defect layers is investigated. It is shown that the cubic nonlinear polarization leads to the effect of bistability on the frequencies of defect modes.

Response of two-defect magnetic photonic crystals to oblique incidence of light: Effect of defect layer variation

The transmission characteristics of a two-defect magnetic photonic crystal (MPC) with respect to oblique incident light are investigated, both for circularly polarized as well as linearly polarized light. It is shown that the transmittivity and Faraday rotation angle are very sensitive to a change of light propagation direction inside the MPC. Possible applications of MPCs as Faraday rotators are discussed.

Huge Goos-Hänchen effect for spin waves: A promising tool for study magnetic properties at interfaces

A possibility to observe huge lateral shift (Goos-Hanchen effect) of exchange spin wave reflected from the interface of two ferromagnetic materials is theoretically investigated. The strong dependence of this effect on the exchange coupling between two magnetic media as well as on the magnetic field is obtained. We show that nonzero interlayer exchange is necessary to observe the lateral shift of reflected spin-wave, and this shift can reach values up to a few hundreds of wavelengths. The observed effect can be a useful tool in investigation of the magnetic coupling between two magnetic materials also through nonmagnetic spacer.