Optical vault: reconfigurable bottle beam by conically refracted light

We employ conical refraction of light in a biaxial crystal to create an optical bottle for trapping and manipulation of particles. We show that by just varying the polarization of the input light the bottle can be opened and closed at will. We experimentally demonstrate stable photophoretic trapping and controllable loading and unloading of light absorbing particles in the trap.Comment: 4 pages, 5 figure

Materials processing with tightly focused femtosecond vortex laser beams

This letter is the first demonstration of material modification using tightly focused femtosecond laser vortex beams. Double-charge femtosecond vortices were synthesized with the polarization-singularity beam converter described in Ref [1] and then focused using moderate and high numerical aperture optics (viz., NA = 0.45 and 0.9) to ablate fused silica and soda-lime glasses. By controlling the pulse energy we consistently machine high-quality micron-size ring-shaped structures with less than 100 nm uniform groove thickness.Comment: 8 pages, 3 figures, 10 references; submitted to Appl. Phys. Lett. on May 31, 201

ABOUT DYNAMICS OF THE GEOPOLITICAL POSITION OF THE NORTH-EAST OF RUSSIA IN THE 17-TH-21-ST CENTURIES

Purpose: In the article, the changes in the geopolitical situation on the North-East for four preceding, partial centuries are considered. Methodology: Up to the inclusion in the structure of Russia, this extensive region (2.3 million km2) with the considerable natural-resources potential has actually existed out of the world geopolitical processes, basically, because of the extremeness of the natural climatic conditions, remoteness from the centers of world civilization and limited technical and technological capabilities in those times. Result: The different stages in the state of the geopolitical position of the region in prior centuries are identified and their repeatedly and multidirectional varying characteristics during the period in question are reported. It is also emphasized that the measures attempted by Russia for strengthening of the geopolitical position on the North-East gave rise abroad to the negative response consonant with the current ones practically at all considered stages. The current stage is considered as a period of the drastically varying external geopolitical conditions and increased technical capabilities when the geopolitical significance of the North-East for Russia increases by a factor of many times. Applications: This research can be used for universities, teachers, and students. Novelty/Originality: In this research, the model of About Dynamics of the Geopolitical Position of the North-East of Russia in the 17-th-21-st Centuries is presented in a comprehensive and complete manner