We have demonstrated remarkable enhancement of longitudinal and transverse magneto-optical Kerr effects in magnetoplasmonic crystals based on thin nanostructured films of nickel and iron due to resonant excitation of magnetoplasmonic waves in Faraday and Voight configurations . Manifestations of ultrafast time-dependent transverse magneto-optical Kerr effect are experimentally demonstrated in femtosecond laser pulses reflected from a one-dimensional magnetoplasmonic crystal. We show that exciting surface plasmon-polaritons with magnetization-dependent dispersion law allows one to control the shape of the refected pulse.
Temporal profile distortion of a femtosecond pulse reflected from one-dimensional plasmonic crystal have been
studied using time-resolved cross-correlation technique. Spectral dependences of cross-correlation functions show
that SPP resonance with Fano-type lineshape strongly disturbs reflected pulse on picosecond timescale.
Optical chirality is reported in a silver thin film with an ordered array of subwavelength Z-shaped apertures. Normal
incidence transmission of right-hand circular polarized light through the planar chiral nanostructure is found
to be sensitive to the direction of the light propagation resembling well-known circular dichroism phenomenon.
The relative transmission difference is increased in the spectral vicinity of the surface plasmon resonances and
reaches 0.11. The azimuthal dependences of elliptization of light state are shown to depend upon the direction
of light propagation and this effect is also addressed to optical chirality of the specimen. It is experimentally
demonstrated that the metamaterial could be substituted for anisotropic lossy medium whose tensors of real and
imaginary parts of permittivity are diagonalized in different Cartesian coordinate systems. The angle between
these systems is experimentally found to reach 10° in the site of plasmon resonances.
The results of experimental observation of magneto-optical Kerr effect (MOKE) enhancement caused by surface
plasmon-polaritons (SPP) excitation in 1D and 2D magnetoplasmonic crystals are presented. One-dimensional
nickel magnetoplasmonic crystals have periodic structure formed by periodic nickel grooves made on nickel
surface. The period of the structure is 320 nm and the depth of the grooves is 50 nm. The second group of the
samples represents itself a 2D self-assembled hexagonally ordered monolayer of polystyrene (PS) microspheres
with diameters from 500 to 760 nm and covered by 100- nm - thick nickel film. MOKE measurements performed
in transversal configuration demonstrate that SPP excitation lead to transversal Kerr effect (TKE) enhancement
resulting as a sharp peak in TKE spectrum.
Strong linear birefringence and dichroism is observed in optical metamaterial consisting of array of subwavelength
elliptical holes in a silver film. Spectroscopic polarimetic measurements reveal structure's ability to convert linear
polarized light by making it highly elliptical (ellipticity up to 1) and rotating the polarization plane by angles up
to 90°. Refractive index difference for two eigenstates of the structure extracted from experimental data varies
from 0.4 to 1.8 in the visible. Linear birefringence and dichroism effects together result in metamaterial's ability
of separating frequency modes by putting them into different polarization modes.
Optical second harmonic generation (SHG) in amorphous Si/SiO<sub>2</sub> multiple quantum wells (MQW) is studied by means of SHG spectroscopy, SHG interferometric spectroscopy and X-ray double-axes reflectometry of the MQW samples with the Si quantum well thickness <i>d</i> ranging from 1.00 to 0.25 nm. The electron density profiles obtained from X-ray reflectometry data confirm multilayer structure presence and refine growth data on <i>d</i> values. The observed modification of the SHG spectra upon decreasing <i>d</i> is interpreted using combination of the resonant two-subband approximation for the nonlocal optical response of each quantum well with the generalized transfer-matrix formalism for the description of light propagation across the whole MQW structure. Agreement with the experiment shows that the description of the quadratic optical response of the MQW structure within the model of a nonlocal piecewise-continuous medium remains valid on the sub-nanometer scale.
The enhancement of the second-harmonic generation (SHG) in all-silicon coupled microcavities (CMC) based on one-dimensional photonic crystals is experimentally studied. CMC are fabricated from alternating layers of electrochemically grown mesoporous silicon and consist of two identical half-wavelength-thick cavity spacers separated by additional porous silicon photonic crystal. The enhancement of the second-harmonic response of CMC in the vicinity of splitted cavity modes is experimentally observed in both angular (wave vector) and frequency domain spectra. The variation of transmission of the intermediate photonic crystal, which controls the interaction between coupled cavity spacers, leads to monotonic dependence of the SHG resonances splitting on the number of pairs of the intermediate Bragg reflector.
The spatial distribution of the local optical field at the cleavage of photonic crystal smicrocavity has been obtained by the scanning near-field optical microscope (SNOM). The localization of optical radiation at microcavity resonant wavelength in the vicinity of the λ/2 spacer layer is demonstrated. Samples of photonic crystal microcavity are prepared from silicon wafer by electrochemical etching technique. The wavelength of the microcavity mode is optimized for resonance with wavelengths of lasers. The image of the spatial distribution of optical field at the cleaved edge of the facing vertically microcavity is observed. Sample is pumped through external single-mode fiber perpendicularly to the microcavity. SNOM
operates in the collection mode with the apertureless tip. We observe the localization of the resonant optical field in microcavity but we do not reveal such localization of the radiation at the non-resonant wavelength.
The enhancement of the third-harmonic generation (THG) in photonic crystal microcavities fabricated from alternating layers of mesoporous silicon is experimentally studied. Two types of THG resonances are observed in the third-harmonic intensity spectra measured in both angular and frequency domains. The THG enhancement is obtained as the fundamental radiation is in the resonance with the cavity mode and is attributed to the spatial localization of the fundamental field inside the cavity spacer and the fulfillment of the phase-matching conditions for THG. The intensive THG response is also observed as the fundamental radiation is tuned across the photonic band gap edge and is supposed to be attributed to the THG phase-matching. Additional factor for the THG enhancement is the three-photon resonance of the porous silicon cubic susceptibility.