T. V. Murzina

Second harmonic generation in multilayer graphene induced by direct electric current

Optical second harmonic generation (SHG) is studied from multilayer graphene films in the presence of DC electric current flowing in the sample plane. Graphene layers are manufactured by chemical vapour deposition (CVD) technique and deposited on an oxidised Si(001) substrate. SHG intensity from graphene layer is found to be negligible in the absence of the DC current, while it increases dramatically with the application of the electric current. The current-induced change of the SHG intensity rises linearly with the current amplitude and changes its sign under the reversal of the current direction to the opposite. The observed effect is explained in terms of the interference of second harmonic radiation reflected from the Si surface and that induced by the DC current in multilayer graphene.

Surface-Enhanced Optical Third-Harmonic Generation in Ag Island Films

Surface-enhanced optical third-harmonic generation (THG) is observed in silver island films. The THG intensity from Ag nanoparticles is enhanced by more than 2 orders of magnitude with respect to the THG intensity from a smooth and homogeneous silver surface. This enhancement is attributed to a local plasmon excitation and resonance of the local field at the third-harmonic wavelength. The diffuse and depolarized component of the enhanced THG is associated with the third-order hyper-Rayleigh scattering in a two-dimensional random array of silver nanoparticles.

Mesoporous silicon photonic structures with thousands of periods

In this work, we present the results on the fabrication and characterization of the structural and optical properties of thick mesoporous silicon-based 1D photonic crystals (PC) containing up to 2500 periods (400 μm thick) made by electrochemical etching in the hydrofluoric acid solution. The composition of multilayered structures with good spatial periodicity up to thousands of layers and with good reproducibility of porosity of alternate layers is demonstrated that is proven by SEM measurements. Comparative studies of the reflectivity spectra from the front and back sides of a thick free-standing PC also testify a good periodicity of the multilayer structure which manifests itself by the appearance of the photonic band gaps. We demonstrate that the main mechanism that restricts the fabrication of thick porous silicon-based photonic crystals is the local decreasing of the HF concentration in pores.

Nonlinear magneto-optical Kerr effect and plasmon-assisted SHG in magnetic nanomaterials exhibiting giant magnetoresistance

Abstract Optical second harmonic generation (SHG) and nonlinear magneto-optical Kerr effect (NOMOKE) are experimentally studied in Co x Ag 1− x and (CoFe) x (Al 2 O 3 ) 1− x granular films which exhibit giant magnetoresistance (GMR) effect. Nonmonotonous dependences of the magnetoresistance, SHG intensity and NOMOKE magnetic contrast on volume fraction of the magnetic component x are found. The maximum of the NOMOKE magnetic contrast is attained at the value of x close to that providing the maximum of the magnetoresistance. The resonances observed in the SHG spectra are associated with the local surface plasmon modes at the granule/host interfaces.

Nonlinear magneto-optical Kerr effect in hyper-Rayleigh scattering from layer-by-layer assembled films of yttrium iron garnet nanoparticles

Magnetization-induced second-harmonic generation (SHG) in layer-by-layer assembled films containing yttrium iron garnet nanoparticles is observed. The SHG intensity, including its magnetoinduced component, linearly increases with the number of self-assembling layers, which indicates along with diffuseness of the SHG radiation that SHG occurs in its incoherent form: hyper-Rayleigh scattering (HRS). The nonlinear magneto-optical Kerr effect in HRS has a noticeable magnetic contrast brought about by the internal homodyne mechanism.

Optical second harmonic generation probe of two-dimensional ferroelectricity

Optical second-harmonic generation (SHG) is used as a noninvasive probe of two-dimensional (2D) ferroelectricity in Langmuir-Blodgett (LB) films of the copolymer vinylidene fluoride with trifluoroethylene. The surface 2D ferroelectric-paraelectric phase transition in the topmost layer of the LB films and a thickness-independent (almost 2D) transition in the bulk of these films are observed in temperature studies of SHG.

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.

Nonlinear magneto-optical Kerr effect and second harmonic generation interferometry in Co–Cu granular films

Magnetoinduced effects in second harmonic (SH) generation are experimentally studied in the CoxCu1−x granular films. Significant nonlinear magneto-optical Kerr effect (NOMOKE) is observed both in longitudinal and transverse configurations. The interference of the SH fields generated by the interface and bulk, nonmagnetic and magnetoinduced nonlinear polarizations is discussed as a mechanism of NOMOKE enhancement. The bulk nonmagnetic dipole quadratic susceptibility of Co nanocrystals stems from the lack of inversion symmetry in the Co granules.

Two‐Photon Luminescence and Second‐Harmonic Generation in Organic Nonlinear Surface Comprised of Self‐Assembled Frustum Shaped Organic Microlasers

An ultrathin nonlinear optical (NLO) organic surface composed of numerous self-assembled frustum-shaped whispering-gallery-mode resonators displays both two-photon luminescence and second-harmonic-generation signals. A super-second-order increase of the NLO intensity with respect to pump power confirms the microlasing action and practical usefulness of the NLO organic surfaces.

Chirality in nonlinear-optical response of planar G-shaped nanostructures

Chirality effects in optical second harmonic generation (SHG) are studied in periodic planar arrays of gold G-shaped nanostructures. We show that G-shaped structures of different handedness demonstrate different SHG efficiency for the left and right circular polarizations, as well as the opposite directions of the SHG polarization plane rotation. The observed effects are interpreted as the appearance of chirality in the SHG response which allows clear distinguishing of two enantiomers.