Volume 26, Nº 2 (2018)

Resistance of a water-cooled polycrystalline diamond window is experimentally studied in the beam of the 10-kW fiber laser. The irradiated zones are 4 and 0.4 mm in diameter. It is shown that the transmitted beam is not distorted when the power density increases to 7 MW cm⁻². It is found out that the temperature difference of a few hundreds of degrees between the center of the diamond window and its water-cooled edge does not deteriorate the distribution quality of the laser beam transmitted through the window, which allows the arising thermal lens to be corrected.

The processes of laser-assisted formation of elongated Au nanoparticles and their subsequent agglomeration and fragmentation have been experimentally investigated. Elongated gold nanoparticles were formed by laser ablation of a solid target in water. IR radiation of ytterbium-doped fiber laser with a pulse width of 200 ns and a pulse energy of 0.5 to 1 mJ was used to this end. The extinction spectra and transmission electron microscopy images indicate the formation of elongated gold nanoparticles. The interaction of laser radiation with aqueous colloids of elongated nanoparticles in dependence of the pulse energy and exposure time has been analyzed. Possible processes of laser-assisted formation of elongated Au nanoparticles and their subsequent transition from agglomeration to fragmentation of gold nanoparticles, induced by laser irradiation are discussed.

The fabrication of solar cells based on laser-modified silicon (LMS) has been experimentally investigated. Laser ablation of single-crystal Si in air results in the formation of a quasi-periodic array of microcones. After removing the oxide layer, this array is coated by a transparent conducting tin oxide layer. A comparison of the spectral dependence of the mirror reflection of laser-modified Si with that of the initial flat Si surface shows a 10 to 15% drop in reflectivity. The light-to-electricity conversion efficiency is shown to exceed that of the initial flat Si surface by more than 20%.

Spectral characteristics of thin-film nanowire grid polarizers based on amorphous silicon are numerically investigated. The extinction ratio, transmission coefficients, and reflection coefficients are calculated using the MC Grating code based on the rigorous coupled-wave analysis. It is found out that at particular structure parameters of the nanowire grid polarizer the extinction ratio increases to 10⁶ at the optical radiation wavelength of about 380 nm, which is characterized as a quasi-resonance effect. A dissipative-interference qualitative interpretation of this effect within the waveguide model is proposed. This interpretation is confirmed by the calculated field distribution patterns in the vicinity of the quasiresonance.

Integrated-optical waveguides with a nematic liquid-crystal 4-cyano-4’-pentylbiphenyl (5CB) waveguiding layer have been investigated for different polarizations of incident laser radiation and under a pulsed-periodic electric field. A dependence of the damping coefficient of waveguide modes and the sizes of quasi-steady-state irregularities of nematic liquid-crystal layer on the linear polarization of laser radiation and the strength of pulsed-periodic field has been found experimentally. The correlation length is estimated for waveguiding layer irregularities. The waveguide scattering method has provided a resolution in correlation length exceeding the classical resolution limit by approximately an order of magnitude. The observed decrease in the damping coefficient of waveguide modes and irregularity sizes under external field is explained by the decrease in the correlation length of director fluctuations.

The method of multiview full-resolution autostereoscopic imaging based on a temporal alternation of polarization-coded pairs of the full-screen resolution view images is suggested. In general, autostereoscopic K-view (K > 2) image without flicker can be formed with a K/2-fold increase in a frame rate as compared with the minimum (60 Hz) one. The corresponding optical layouts comprise an amplitude-polarization matrix imager, a passive polarization parallax barrier, and an active amplitude parallax barrier. The characteristic requirements are indicated for the liquid crystal components of the layouts depending on the order of their mutual location.

The aim of this analytical study of a plasma-filled rectangular cavity in time domain is to exhibit the ability of the evolutionary approach to study the electromagnetic fields forced by surge signals in a dynamical system. Maxwell’s equations for the fields and the boundary conditions for the perfect electric conductor rectangular cavity are supplemented with the constitutive relation for the plasma. Two different pulse waveforms were used for modeling of the surge signals exciting the fields. The solution is obtained for the dynamical system in the form of product of two elements. First element that depends on coordinates is a modal basis. The other element depending on time is a modal amplitude. The modal basis is specified as a summation of four subspaces. Two of these subspaces resemble the solenoidal modes, and the other two resemble the irrotational modes. Evolutionary differential equations with initial conditions are obtained and solved analytically for the amplitudes.

Results of a computer simulation of the resolution of three noise sources with different intensities against the background of isotropic noise in an oceanic waveguide are presented. A comparative analysis of the error in determining their coordinates (bearing, radial velocity, distance, depth) is performed. A computational experiment is implemented based on the interferometric method of source localization using vector-scalar receivers.

The authors apologizes for this error in the paper “Nonlinear Absorption of Non-Chain HF Laser Radiation in Germanium” by E.E. Alekseev, K.N. Firsov, S.Yu. Kazantsev, I.G. Kononov, and V.E. Rogalin.

On page 280, Affiliation by K.N. Firsov, S.Yu. Kazantsev, and I.G. Kononov must be written as

K. N. Firsov^2,3

²Prokhorov General Physics Institute of the Russian Academy of Sciences, ul. Vavilova 38, Moscow, 119991 Russia

³National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Kashirskoe sh. 31, Moscow, 115409 Russia

S. Yu. Kazantsev²

²Prokhorov General Physics Institute of the Russian Academy of Sciences, ul. Vavilova 38, Moscow, 119991 Russia

I. G. Kononov²

²Prokhorov General Physics Institute of the Russian Academy of Sciences, ul. Vavilova 38, Moscow, 119991 Russia