Generation of propagation-invariant light beams from semiconductor light sources

We have studied the possibility of generating propagation-invariant (nondiffracting) light beams using various semiconductor sources of radiation. The propagation-invariant (Bessel) beams have been generated using cone-shaped lenses (axicones) with an apical angle of 178° and 170°, which provided beams with a central spot diameter of 100 and 10 μm, respectively. The radiation sources were represented by various types of light-emitting diodes, quasi-single-mode semiconductor vertical-cavity surface-emitting lasers and broad-stripe (100 μm) edge-emitting laser diodes. It is demonstrated that these semiconductor light sources offer a promising basis for the generation of propagation-invariant light beams in various devices (including optical tweezers) intended for manipulating micro- and nanodimensional objects.     

Generation of π modes in semiconductor vertical-cavity surface-emitting lasers

We have theoretically and experimentally studied optical emission from the side faces of mesa structures for vertical-cavity surface-emitting lasers (VCSELs). The results of spatially resolved spectral measurements show that a new type of lasing modes is found in VCSELs with circular mesa structures, which corresponds to the π mode propagation along the mesa diameter with reflection from the sloped walls and the bottom Bragg mirror.     

Optoelectronic Measuring Systems for High-Voltage Installations Based on Photovoltaic Converters

Measurement Techniques - We consider the main principles of construction of optoelectronic measuring systems in which the electric power supply of measuring modules is realized with the help of...     

Surface Factor in Incompressible Liquid Film Flow

The results of investigation of the influence of a solid surface on the film flow of a viscous incompressible liquid in a gravitational field are analyzed. Using the dimensional method, a generalized similarity criterion for a film flow has been obtained. The laboratory facility and the method for investigating the film flow for various types of packing elements are described.     

Production of Initial Compounds for Spinellide Ceramics by the Chemical Precipitation Method

The processes of synthesis of initial compounds for magnesium spinel in chemical precipitation are studied. It is established that the choice of initial salts (nitrates, chlorides, sulfates) has virtually no effect on the phase composition of heat-treated products; however, it has a significant effect on the properties of the initial precipitates.     

Parametric criteria of reliability and nondamageability for the dam of the Sayano-Shushenskoe hydroelectric station

Power Technology and Engineering -