Correlation Optics, Coherence and Optical Singularities: Basic Concepts and Practical Applications

Abstract

The main idea of this review is to trace the interrelations and inter-transitions between the basic concepts and approaches of the correlation optics (including the light coherence) and the singular optics dealing with networks of “exceptional” points of light fields. The principles and examples are described of formation of light fields with required structures (amplitude, phase and polarization distributions, spectral properties as well as the internal energy flows and energy gradients responsible for optical forces) via superpositions of model optical fields of simple standard configurations and under controllable correlation conditions. The theoretical and experimental results, obtained by the authors and other researchers, demonstrate possibilities of the general approach to the complex fields formation with spatial and polarization inhomogeneities. A special topic, considered in more detail, is the interaction of structured optical fields with the media containing suspended micro- and nanoparticles, their inhomogeneous heating by the laser radiation and the accompanying self-diffraction and self-focusing phenomena. Possible light-induced phase transitions and controllable generation of the gas-vapor microbubbles in the medium are discussed. Specific optical singularities in polychromatic light fields are analyzed in connection to the field coherence. Some experimental solutions for revealing the fine structure of optical fields by means of the interference schemes are presented. Practical applications for the micromanipulation techniques, optical diagnostics of remote and random objects, optical treatment and laboratory practice in biology and medicine are described and discussed.

Optical phase singularities: Physical nature, manifestations and applications

“…The most convincing evidence for the entanglement of photon states is obtained when not "pure" LG modes are detected in the channels, but their superpositions. For example, state (7) can be represented in the form (8) where a 0 and a 1 are real numbers, and the normalization condition a 2 0 + a 2 1 1 is required (here only the two first…”

“…This vibrant activity resulted in establishment of "structured light" as a new fruitful paradigm of physical optics [1][2][3][4][5][6]. The structured optical fields find interesting and productive applications in various branches of optical technologies, optical manipulations, optical communications and data processing as well as in optical diagnostics [7,8].…”

“…in space where certain parameters characterizing the field spatial structure (phase, ellipticity or helicity of polarization) are indeterminate. Despite the variability of types and sorts of optical singularities [9][10][11][12][13][14][15][16][17][18][19][20][21][22], they possess many similar features and are inherently interrelated (for example, the polarization singularities can be treated as phase singularities of separate orthogonal components of vector light beams [8,16,23]). The main common feature of optical singularities is their topological nature which makes the singularity stable with respect to small perturbations [24] and determines that each singularity qualitatively "organizes" the whole field in its vicinity, and different singularities combine and interact according to general laws.…”

“…This task is quite compatible with the second goal, apparently much more utilitarian: description of some practical possibilities, offered by singular optics in analysis of chaotic speckle fields, and their use for reconstruction of scattering objects generating these fields. By the general approach, this paper adjoins our previous reviews on the adjacent topics [7,8], and may be considered their further development and addition.…”