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Multi-wavelength nonlinear parametric χ⁽³⁾-effects were observed in highly transparent Y₂O₃ and Y₃Al₅O₁₂ nanocrystalline ceramics under picosecond pumping at 300 K. All recorded Stokes and anti-Stokes components in the visible and near IR were identified and attributed to the stimulated Raman scattering active vibration modes of these novel optical and laser-host crystalline materials. For both materials, the steady-state first-Stokes Raman gain coefficient was estimated at a wavelength of around 1 μm.

We propose a novel nonlinear optical spectroscopic technique H-CARS (Hyper Coherent Anti-Stokes Raman Spectroscopy) to allow imaging of biological structures in real time.

Non-perturbative time-dependent calculations of single and double ionization of a one-dimensional model of atomic calcium by short and intense laser pulses were performed at various wavelengths. The comparison of the probabilities calculated within a two-active electron (TAE) approach with those obtained using a single-active electron (SAE) approximation clearly demonstrates the crucial role played by the electronic correlation and by doubly excited states within this model, even for the formation of Ca⁺.

The strong-field molecular dynamics is studied by direct numerical integration of the non-stationary Schroedinger equation for laser pulses of femtosecond duration. The calculations are performed beyond the Born–Oppenheimer approximation with both electronic and rotational degrees of freedom being taken into account. The rotational dynamics is confirmed to play a significant role during molecular ionization. Nevertheless, a range of parameters is found that provide molecular ionization to be correctly described under assumption of ``frozen'' molecular axis orientation. Using this model the results of 3D electron dynamics of a molecule are obtained. For ultrashort pulses a 3D account of the electronic degrees of freedom is proved to provide a full description of the strong-field molecular behavior.

Detailed experimental analysis of photon echo polarization in a longitudinal magnetic field is performed for the first time at the simplest quantum transition J = 1 ↔ J = 0 for which the non-Faraday rotation of photon echo polarization plane was predicted. The echo was generated at the intercombination transition (6s6p) ³P₁ → (6s²) ¹S₀ of ¹⁷⁴Yb by two resonant laser pulses of linear (parallel or mutually orthogonal) polarization, and the angled echo optical scheme was applied for the detection. At the magnetic field strength ℬ ⩽ 5 G the photon echo has polarization very close to linear one; its polarization plane rotates around magnetic field vector, and photon echo polarization components and integral echo power oscillate versus ℬ from its maximum value to zero, in agreement with theory. At a stronger magnetic field ℬ ∼ 40 G photon echo power oscillations disappear, no preferable orientation of polarization vector is observed; the fluctuations of exciting radiation spectrum are supposed to be responsible for this "non-polarized" echo.

Second- and third-harmonic generation in silicon carbide (SiC) nanopowders embedded in a polymethyl methacrylate (PMMA) film are studied using nano-, pico-, and femtosecond laser pulses. Second- and third-harmonic generation processes are shown to allow the detection of absorptive agglomerates of nanocrystals in transparent materials and the visualization of optical breakdown in nanocomposite materials. Polarization of the third-harmonic signal is shown to be highly sensitive to the polarization of the pump field, permitting third-harmonic generation to be used as a probe for the anisotropy of nanocomposite materials. The second-harmonic signal, on the contrary, has no memory of the initial polarization state of the pump field and is, consequently, ideally suited as a measure of orientation-averaged nonlinearities of nanopowder materials.

On the basis of classical electrodynamics the reflection and transmission of a few-cycle femtosecond Ti:Sa laser pulse impinging on a thin metal layer have been analysed. The thickness of the layer was assumed to be much smaller than the skin depth of the radiation field, and the metallic electrons were represented by a surface current density. The interaction of the electrons with a periodic lattice potential has also been taken into account. The presence of this nonlinear potential leads to the appearance of higher harmonics in the scattered spectra. A formal exact solution has been given for the system of the coupled Maxwell-Lorentz equations describing the dynamics of the surface current and the radiation field. Besides, an analytic solution was found in the strong field approximation for the Fourier components of the reflected and transmitted radiation. In our analysis particular attention has been paid to the role of the carrier-envelope phase difference of the incoming few-cycle laser pulse.

Hair follicles have been assigned an increasingly significant role in dermatopharmacology. Previous studies have shown that the penetration of substances into the follicle depends on its activity. Telogen follicles that were not producing sebum were closed for follicular penetration. The present study uses optical coherence tomography (OCT) to show that the orifices of inactive follicles are blocked by plugs formed of corneocytes. The follicular penetration of a fluorescent dye was analyzed by cyanoacrylate surface biopsies in combination with laser scanning microscopy. Surface exfoliation and cyanoacrylate surface peels were used as a pre-treatment to remove the corneocyte plugs from the follicular orifices and therefore to open up closed follicles. It was shown that both procedures could increase the number of open hair follicles significantly. The present experiments show that OCT in combination with laser scanning microscopy is an excellent non-invasive in vivo method for the investigation of hair follicle properties and follicular penetration processes.

A mixture of the multicomponent Bose-Einstein condensate is considered, where each component moves with its own velocity. As a result of the relative motion, the mixture stratifies when the relative velocity reaches a critical value. Stability conditions for a binary moving mixture are derived and the critical velocity is found.

Specially designed LiNbO₃ electrooptic shutter was used for Q-switching of Er:YAG laser system. Brewster angles was employed at the Pockels cell LiNbO₃ crystal faces to avoid the insertion of a polarizer into the resonator. By help of the theoretical analysis based on Jones calculus, the dependency of Pockels cell radiation transmission on applied voltage was found. Theoretically and experimentally was proved, that for 25 mm long LiNbO₃ crystal the voltage of 1.5 kV is sufficient to avoid the laser oscillation. With this Pockels cell a stable running Q-switched Er:YAG laser system was realized. The generated giant pulse length and energy was 70 ns and 30 mJ, respectively.