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We report an experimental study of the influence of pulsed 1064-nm laser light polarisation on the dc photovoltage response of nanographite films. The amplitude of the pulsed potential difference generated in the films across the plane of incidence is an even function of the angle between the plane of polarisation and the plane of incidence of the laser beam, and that along the plane of incidence is an odd function of this angle. We present empirical relations between the incident pulse power, parameters of elliptically polarised laser light and photovoltage amplitude. The results are interpreted in terms of surface electric currents due to the quasi-momentum transfer from the incident light to the electron system via interband quantum transitions and the surface photogalvanic effect.

Nonlinear scattering of 1064-nm laser light in an aqueous suspension of purified carbon nanotubes has been studied in relation to their optical power limiting behaviour using z-scan measurements to simultaneously determine the energy and shape of the transmitted and 90° circ-scattered pulses. The results indicate that the reduction in transmitted laser pulse energy with increasing incident power density is mainly due to the associated increase in scattered pulse energy. The shape, duration and time shift of the transmitted and 90° circ-scattered pulses are intricate functions of incident power density. The data are interpreted in terms of thermally induced nonlinear and Rayleigh scattering processes at high and low incident power densities, respectively.

We have studied the effect of nanosecond laser pulses (λ = 1064 nm) on the optical properties of onion-like carbon (OLC) prepared by high-temperature vacuum annealing of detonation nanodiamond and dispersed in N,N-dimethylformamide (DMF). The results demonstrate that, under low-intensity irradiation, the OLC suspension displays optical limiting behaviour. Increasing the incident intensity leads to bleaching of the suspension in the visible and near-IR spectral regions.

The efficiency of hydrogen evolution from transformer oil into a vacuum and into air under normal pressure is studied for the case when the oil is exposed to focused ultrasonic radiation. The study is performed by the method of spectroscopy of biharmonic-pumping coherent anti-Stokes Raman scattering (CARS) based on stimulated Raman scattering (SRS). Ultrasonic radiation at a frequency of 1.76 MHz is excited by a spherical piezoceramic transducer mounted on the bottom of the vessel and is focused on the surface of the oil. This causes the intense stirring of the oil with the formation of a fountain. The room-temperature diffusion coefficient of hydrogen in the transformer oil, 10−7 m2/s, is found by approximating experimental data by a theoretical relationship for hydrogen evolution into air. It is shown that ultrasonic radiation with a power density of 2.2 kW/m2 accelerates diffusion processes ten-to fifteen-fold.

CARS diagnostics of hydrogen in rarefied gas mixtures is performed using the biharmonic laser pump based on the SRS by the vibrational hydrogen transition. The diagnostics is shown to be substantially affected by collisions, which result in variations in the linewidth and the frequency of the Raman-active transition. This influence is distinctly observed at pressures higher than 0.05 atm and depends on the composition of the buffer gas mixture.

It is shown that the dependence of the reflection coefficient of absorbing media (metals) on the polarisation of light may give rise to an anisotropy of the absorption of powerful laser radiation in these media. This anisotropy is demonstrated by bending of the laser damage channel. When the polarisation of light is linear, such bending occurs in a plane perpendicular to the plane of polarisation and the direction of bending is governed by an asymmetry of the distribution of the intensity in a cross section of the beam in this plane. The effect is weaker when the polarisation is circular. The position of the bending plane is then governed by the nature of the asymmetry of the distribution of the intensity over the beam cross section.

A study was made of stimulated Raman scattering in molecular hydrogen with the aim of optimising a generator of biharmonic laser pumping suitable for quantitative analysis of hydrogen by the coherent anti-Stokes Raman scattering method. It was found that, for a fixed experimental geometry and a given energy of pulsed input pump radiation, there was an optimal compressed gas pressure at which the biharmonic pumping efficiency was maximal.

An efficient YAG:Nd3+ laser was passively Q-switched by an LiF: crystal. Laser radiation was generated as a single longitudinal mode even when the pump energy reaching the active medium was varied in a wide range.

Conditions were found for the most effective suppression of the forward (concurrent) stimulated Raman scattering in hydrogen subjected to monochromatic laser pumping.