Lidar sensing of tectonic aerosol fluctuations in the laser strainmeter–interferometer tunnel during 2017.12–2018.05 at the Schultz cape (131°9′8″ E, 42°34′6″ N) near Vladivostok was performed for the first time to our knowledge. A negative correlation of laser interferometer and aerosol lidar signals was observed during low-frequency Earth crust deformations.

A method for switching the regime of single-frequency generation of nanosecond pulses to a train of picosecond pulses in the Nd:YAG laser with an electro-optic Pockels Q-switch without changing cavity elements is proposed. The single-frequency regime was provided by aligning an active element which played the role of a longitudinal cavity mode selector. The lasing spectrum was measured using a Fabry-Perot interferometer with simultaneous recording of pulse oscillograms.

West Spitsbergen fjords have been probed (on shipboard) by a compact Raman lidar (Wave Research Center, Prokhorov General Physics Institute, Russian Academy of Sciences), based on a pulsed diode-pumped Nd3+:YVO4 laser with frequency doubling, in August, 2011. The evolution of lidar signal spectra (Raman, fluorescence, and elastic scattering) when approaching the Paulabreen glacier of the Rinders Fjord has been measured. A new phenomenon was discovered: the formation of an immiscible layer of relict thaw water from the glacier on the sea surface. An increase in the layer thickness (to 5–10 cm near the glacier) was accompanied by a decrease in the layer temperature (which was determined by measuring the distortion of the OH Raman band) and the content of phytoplankton and dissolved organic matter to zero, with a simultaneous increase in the Rayleigh scattering amplitude and a change in the surface color from blue to gray. Smoothing of the rippled sea surface (covered by relict water) at the border of the wake trace (which it rolled down from) was observed for the first time, as far as we know. The mechanism of the formation of a supercooled (t ⩽ 0°C) layer and screening the heat diffusion, which reduces the contribution of the relatively warm sea water (≈3°C) to the thermal balance of Arctic and global climate, is discussed.

Compact Raman LIDAR system for remote sensing of sea and drifting ice was developed in Wave Research Center at Prokhorov General Physics Institute of RAS. Diode pumped solid state laser (532 nm, 5 ns, 200 mu J/pulse, 1 kHz) in combination with grating spectrograph equipped with gated detector (ICCD) resulted in high sensitive detection with wide spectral range. Light weight (similar to 20 kg), small dimensions and low power consumption (similar to 300 W) make it possible to install such system on any vehicle including unmanned aircraft system. Drifting ice and sea water in Rindersfjord was characterized by Raman spectroscopy and fluorescence. Temperature, phytoplankton concentration and dissolved organic matter (DOM) of sea water were detected in Icefjord, Van Mijenfjord and Rindersfjord. These fjords are good examples of different influence of Greenland Sea and glaciers on water mass transfer and temperature distribution. It was found that Paulabreen glacier strongly influence on water mass transfer and temperature in Rindersfjord. Surface water temperature decreased for more than 3 degree while arriving to glacier front at Rindersfjord. Abnormal temperature gradient of surface water near Akseloya Island was observed. The possible mechanism of this phenomenon is discussed. Influence of relict melted water from Paulsbreen glacier on chlorophyll and DOM distribution in fjord was estimated. Possible applications of compact LIDAR systems for express monitoring of sea water in places with high concentration of icebergs or near ice streams in Arctic Ocean are discussed.

The evolutions of the signals of the elastic (Mie) and Raman backscattering of the Nd:YAG laser second-harmonic radiation in the upper layer of the sea under cavitational perturbation induced by the passage of a high-speed boat are compared under the conditions of the outdoor experiment. It is shown that the signal of the elastic scattering on bubbles returns to the background level within the time of ∼10 min. The relaxation time of the spontaneous Raman scattering signal can be an order of magnitude larger than this value (the evaluated value under the particular conditions of this experiment is ∼120 min). Interpretation is given to this difference in attenuation time of the elastic and inelastic scattering signals at the cavitational perturbation of the sea.

The dynamics and energy spectra of electrons driven by a relativistically intense laser pulse are analyzed. The description is based on the numerical solution of the relativistic Newton’s equation with the Lorentz force generated by a strong focused optical field. After the interaction with it, electrons retain a considerable fraction of the energy of their oscillations during the interaction. The electron postinteraction energy spectrum is calculated. The energies in the spectrum high-energy tail are determined by the laser pulse intensity at the focal spot. An approach to estimating absolute values of the laser pulse intensity based on the measurement of the energy spectra of the electrons is proposed.

A complex of lecture demonstrations on wave optics with a personal computer used for control, processing, and representation of the experimental data is described in the present paper. A modern photodetector system built around a photodiode strip is used for recording of the light intensity distribution. The results of application of this complex to the study of dual-beam and multibeam interference of light and of the Fresnel and Fraunhofer types of diffraction by different objects are presented. The developed complex of lecture demonstrations allows the students to refine their understanding of the basic physical phenomena in optics. It also allows the teacher not only to visualize the lecture experiment but also to make it quantitative.

Time scanning with an image-converter camera revealed fluctuations of the phase of the conjugated wave. Shifts of the focusing spot of the output beam were observed for a multipulse amplifier with phase conjugation: these shifts were due to phase fluctuations of the conjugated wave.

A compact tunable laser utilizing neodymium-activated phosphate glass is described. A four-pass amplifier with phase conjugation was used to generate output radiation with diffraction-limited divergence. The output energy was 30 J and the pulse duration was 20?50 ns. Efficient optical decoupling with radiation reflected from a target was achieved in the laser.