Table of contents

A review of studies of the properties of radiation from optically coupled lasers is presented. The methods for phase locking the fields in optically coupled lasers of different types are considered and the methods for supermode selection and correction of the radiation pattern are discussed.

A 12-kW continuous-wave chemical oxygen-iodine laser, provided with an original jet-type singlet oxygen generator, is developed and tested. The experimental and numerical techniques applied for the diagnostics and mathematical simulation of processes in the laser active medium are introduced. Some of the calculation and experimental results are presented.

An equation is derived for calculating the TEM_00q-mode energy density in a laser cavity using experimentally measured quantities (e.g., the reflectivity of the output mirror, the pump excess over the threshold, the output energy, and the TEM_00q-mode radius). The equation is used for estimating the saturation energy density in at 2.92-μm Cr³⁺:Yb³⁺:Ho³⁺:YSGG laser

The mechanism of lasing at the Cd II atomic ion transition at 441.6 nm at near-threshold temperatures, when the contribution from the sputtering of a pure metallic cadmium film by charged products of nuclear reaction cannot be neglected, is discussed. A comparison of the theoretical and experimental data leads to a value 10.8 atoms per event for the total average yield of sputtering of cadmium by the products of nuclear reaction ³He(n, p)³T.

Efficient frequency conversion of femtosecond pulses of a Cr:forsterite laser in tapered fibres is experimentally demonstrated. Unamplified 30-fs Cr:forsterite-laser pulses are used to generate the third harmonic in the phase-matching regime. Propagation of 75-fs, 10–200-nJ Cr:forsterite-laser pulses through a tapered fibre in the range of anomalous dispersion is accompanied by multiply phase-matched cascaded four-wave mixing, giving rise to a manifold of new spectral components in the visible range and substantial spectral broadening within the wavelength range from 1300 to 1600 nm.

The possibility of suppressing chaotic oscillations in a bidirectional Nd³⁺ : YAG ring laser with the help of a constant magnetic field is considered. It is shown that the application of a constant magnetic field of a few tens of oersted on the active medium transfers the laser from the synchronous chaos regime to pulsed quasi-periodic generation.

Stimulated Raman self-scattering (SRSS) is shown not to be a unique effect observed exclusively in the propagation of femtosecond optical solitons through optical fibres. SRSS always accompanies the self-action of high-power femtosecond pulses in a variety of media. Unlike classical SRS, SRSS has no lasing threshold and can appear when the pulse spectrum overlaps the band of vibrational resonances of the medium. A classification of the main SRSS regimes is given. The basic features of different regimes of ultrashort-pulse self-scattering are investigated by computer simulation techniques.

An express technique is proposed for the study of stimulated Raman scattering (SRS) in crystals excited by long trains of picosecond pulses. SRS was studied in several crystals excited by 15-ps pulses from an Nd³⁺:CLNGG disordered garnet laser. SRS in SrMoO₄ and Ca₃(VO₄)₂ crystals was obtained and investigated for the first time, and compared with SRS in popular SRS-active BaWO₄ and KGd(WO₄)₂ crystals.

The possibility of using the waveguide scattering of laser radiation for obtaining information on the statistical properties of irregularities from the noisy data obtained in the far-field zone is shown. A complex algorithm for reconstructing the experimental autocorrelation function of the surface roughness of an integrated-optical waveguide substrate is described. This algorithm is based on a combination of the classical regularisation and quasi-optimal filtering.

Light transmission through an array of tunnel-coupled channel waveguides is studied in detail. It is shown that a discrete structure of the light-transmitting medium leads to a modification of the law of light refraction. It is also shown that a new type of total internal reflection of light inside the structure manifests itself in an inhomogeneous array of coupled waveguides. The process of light propagation in an array of identical channel waveguides, which are arranged equidistantly along concentric circles, is investigated. It is established that such a waveguide array is equivalent to an inhomogeneous system of coupled waveguides. The mode excitation process in an array of ring channel waveguides located on cylindrical and conical surfaces is considered.

The theory of whispering-gallery modes (WGMs) in a dielectric spherical layer is developed based on the approximation of Bessel functions by Airy functions. It is shown that the optimal layer thickness exists at which the intensities of WGM fields in the spherical layer are more than an order of magnitude greater than those of WGM fields in a solid sphere.

The possibilities of the method of fluorescence correlation spectroscopy for studying the molecular dynamics in living cells are demonstrated. The method provides point measurements of extremely low concentrations of fluorescent molecules and their diffusion coefficients with a high time resolution in a microscopic volume, which is especially important in pharmacological investigations. A biological model of the interaction of liposomes with a cellular membrane is considered. The diffusion coefficients of fluorescent molecules are measured directly in the living cell cytoplasm.

Plane—parallel optically transparent plates widely used to deflect a part of the beam for the beam intensity measurements or formation of the reference beam in spectrometers and lidars are examined. It is shown that the ratio of intensities of two split-beam components does not remain constant during the entire measurement process. The strong temperature variations of the ratio of intensities of transmitted and reflected beams, formed when splitting NH₃-laser radiation (λ~13 μm) by a 2.7-mm germanium plate with a wedge angle of about 1', are revealed. The mathematical analysis, taking into account not only the temperature dependence of the path-length difference of two rays, one of them passing through the plate two additional times, but also the plate wedging, has provided the explanation of the experimental results.

A new method for measuring the focal distance of a thermal lens in solid-state lasers with short active elements is proposed and tested. The method is based on the quenching of lasing and allows a direct estimate of the focal distance with an error of ~10%.

The three-dimensional moment approach is developed which allows the detailed calculation of the emission spectrum of matter in the wave zone for arbitrary parameters of radiation and matter using the integrated characteristics of interaction of laser radiation with matter. It is shown that ionisation processes can cause the broadening of the emission spectrum that exceeds its blue shift.