Ways to achieve efficient non-local vortex beam generation

Based on the insights into the phenomenon of bound states in the continuum, a novel approach utilizing the momentum-space polarization morphologies of periodic structures to generate vortex beams (VBs) has been proposed. Such periodic structures modulate beams in a nonlocal way and require no precise alignment. However, the efficiency of such an approach has not been analyzed in detail, and the efficiency in previous realizations is far from optimized. Here, we analyze the factors affecting the efficiency of nonlocal VB generation. We show that the maximal efficiency cannot exceed 25% if the periodic structure carries only singlet resonances. To go beyond this limit, we propose two approaches to improve efficiency. We theoretically analyze the mechanisms and verify the approaches by full-wave simulations. Both of the approaches serve to improve the generation efficiency by several folds.

Using Borehole Seismic Data in Designing of Development and Further Exploration of Oil Fields

Borehole seismology allows studying the specific features of the geological structure and physical properties of deposits in the borehole environment using waves of various kinds based on the analysis of characteristics of these waves, their rates propagation, attenuation, space polarization, and the nature of rock anisotropy. The research is intended to study the wave fields of various types of waves taking into account their dynamic, speed and polarization characteristics and the features of geological structure both in the vicinity to the borehole and laterally in the crosshole space. Using the borehole seismology method, the geological structure of reservoirs was specified; a prediction was given as to the development of enhanced reservoir units in the crosshole space.