R. V. Kapra

Magnetization-induced second- and third-harmonic generation in magnetic thin films and nanoparticles

The results of our recent experimental studies of magnetization-induced second- and third-order nonlinear optical effects in magnetic nanostructures are surveyed. Magnetization-induced variations of the intensity, the polarization state, and the relative phase of the second-harmonic wave are studied in magnetic nanogranular films, self-assembling films with garnet nanoparticles, thin magnetic metal films, and Langmuir-Blodgett films containing rare-earth ions. The nonlinear magneto-optical Kerr effect (NOMOKE) in second-harmonic generation (SHG) from thin magnetic and granular films is shown to exceed the linear magneto-optical Kerr effect by at least 1 order of magnitude. Magnetization-induced optical third-harmonic generation (THG) is observed in thin magnetic metal films and nanogranular films. The NOMOKE in THG from these magnetic nanostructures appears to be of the same order of magnitude as the second-order NOMOKE in SHG. The NOMOKE magnetic contrast in the THG intensity is up to ∼0.1 in Co_xAg(_1−x) nanogranular films. For the THG wave, the magnetization-induced rotation of polarization is up to 10° in thin Fe(110) films, and the relative phase shift is up to 70° in thin Co films. The studies of the magnetization-induced quadratic and cubic nonlinear-optical effects show the interconnection between the magnetic, structural, and magneto-optical properties of magnetic nanomaterials.

Magnetization-induced third harmonic generation in magnetophotonic microcavities

Magnetization-induced third harmonic generation was experimentally observed in thin films of bismuth-dopedyttrium-iron garnet. The magnitude of magnetization-induced nonlinear optical response was enhanced through building-in a garnet film into a photonic-crystal microcavity. It was shown that the observed magnetization-induced variations in the third-harmonic intensity were caused by the internal homodyne of interfering weak magnetic and strong nonmagnetic polarization components of the cubic nonlinearity of the garnet.

Magnetophotonic crystals based on yttrium-iron-garnet infiltrated opals: Magnetization-induced second-harmonic generation

Three-dimensional magnetophotonic crystals (MPCs) based on artificial opals infiltrated by yttrium iron garnet (YIG) are fabricated and their structural, optical, and nonlinear optical properties are studied. The formation of the crystalline YIG inside the opal matrix is checked by x-ray analysis. Two templates are used for the infiltration by YIG: bare opals and those covered by a thin platinum film. Optical second-harmonic generation (SHG) technique is used to study the magnetization-induced nonlinear-optical properties of the composed MPCs. A high nonlinear magneto-optical Kerr effect in the SHG intensity is observed at the edge of the photonic band gap of the MPCs.

Atomic-to-mesoscopic scale structural transition in metal–carbon diamondlike composites probed by second-harmonic generation

Structural features of diamondlike metal-doped carbon films are studied by means of optical second-harmonic generation (SHG). A high interfacial sensitivity of the SHG probe and its significant enhancement in metal nanoparticles allows one to distinguish between clusterlike and amorphous atomic scale structure of carbon-metal composites. These films appear to retain a stable amorphous atomic-scale structure in a wide range of metal concentration above the percolation threshold. Atomic-to-mesoscopic scale structural transition in diamondlike metaldoped carbon films is observed, which takes place under the thermal annealing.

Magnetization-induced optical third-harmonic generation in Co and Fe nanostructures

Magnetization-induced optical third-harmonic generation (MTHG) is observed in magnetic nanostructures: Co and Fe nanolayers and granular films containing Co nanoparticles. Magnetization-induced variations of the MTHG characteristics in these nanostructures exceed the typical values of linear magneto-optical Kerr effect by at least an order of magnitude: the maximum of magnetic contrast in the MTHG intensity is up to 0.2, the angle of polarization rotation for MTHG is 10\ifmmode^\circ\else\textdegree\fi{}, and the relative phase shift is up to 100\ifmmode^\circ\else\textdegree\fi{}. Correlation between the concentration dependencies of magnetic contrast in MTHG intensity and coefficient of giant magnetoresistance is observed below the percolation threshold in

Cubic self-action effects in photonic-crystal microcavities

{\mathrm{Co}}_{x}{\mathrm{Ag}}_{1\ensuremath{-}x}

Nanostructured one-and three-dimensional magnetophotonic crystals based on porous silicon and artificial opals

films. This points out the probable relations between mechanisms of these transport and nonlinear magneto-optical phenomena.

Magnetization-induced second- and third-harmonic generation in 3-D and 1-D magnetophotonic crystals

Third-order nonlinear-optical self-action effects in photonic-crystal microcavities have been studied. Considerable defocusing has been observed in a nonlinear microcavity layer with a thickness much smaller than the wavelength. The polarization self-action effect that is manifested as the significant rotation of the polarization plane of laser radiation resonant to the microcavity mode has been observed. It has been shown that the polarization rotation angle is a linear function of the radiation power density.

Magnetization-Induced Third-Harmonic Generation in Nanostructures and Thin Films

Nanostructured one-and three-dimensional magnetophotonic crystals are produced by infiltration of yttrium-iron garnet with bismuth into photonic crystals based on porous silicon and artificial opals. The magnetic properties of the resulting structures are studied by generation of the magnetically induced second harmonics. The magnetic contrast of the second harmonics intensity in the spectral region of the photonic gap edge of the photonic crystal is 10–15%.

Garnet Photonic Crystals Based on the Porous-Silicon Templates

3D and 1D magnetophotonic crystals based on opals impregnated by Bi-substituted iron-yttrium garnet (Bi:YIG) and Bi:YIG-SiO2 paired multilayer structures are fabricated. Magnetization-induced effect (nonlinear magneto-optical Kerr effect) in secondand third-harmonic generation is observed.