Andrey S. Ostrovsky

Generation of the "perfect" optical vortex using a liquid-crystal spatial light modulator.

We introduce the concept of the perfect optical vortex whose dark hollow radius does not depend on the topological charge. It is shown analytically and experimentally that such a vortex can be approximately generated in the Fourier transforming optical system with a computer-controlled liquid-crystal spatial light modulator.

Simple technique for generating the perfect optical vortex.

We propose an improved technique for generating the perfect optical vortex. This technique is notable for the simplicity of its practical realization and high quality of the results. The efficiency of the proposed technique is illustrated with the results of physical experiments and an example of its application in optical trapping of small particles.

Modulation of coherence and polarization using liquid crystal spatial light modulators.

We propose a method for modulation of coherence and polarization of electromagnetic fields, employing two crossed zero-twisted nematic liquid crystal spatial light modulators. In contrast to a similar technique analyzed by Shirai and Wolf [J. Opt. Soc. Am A, 21, 1907, (2004)] our method provides a wide range simultaneous modulation of coherence and polarization. The dependence of the obtained results on different definitions of electromagnetic coherence is considered.

Experimental generating the partially coherent and partially polarized electromagnetic source

The technique for generating the partially coherent and partially polarized source starting from the completely coherent and completely polarized laser source is proposed and analyzed. This technique differs from the known ones by the simplicity of its physical realization. The efficiency of the proposed technique is illustrated with the results of physical experiment in which an original technique for characterizing the coherence and polarization properties of the generated source is employed.

Optimum generation of annular vortices using phase diffractive optical elements.

An annular vortex of arbitrary integer topological charge q can be obtained at the Fourier domain of appropriate phase diffractive optical elements. In this context we prove that the diffractive element that generates the vortex with maximum peak intensity has the phase modulation of a propagation-invariant qth order Bessel beam. We discuss additional advantages of this phase element as annular vortex generator.

The van Cittert-Zernike theorem for electromagnetic fields

The van Cittert-Zernike theorem, well known for the scalar optical fields, is generalized for the case of vector electromagnetic fields. The deduced theorem shows that the degree of coherence of the electromagnetic field produced by the completely incoherent vector source increases on propagation whereas the degree of polarization remains unchanged. The possible application of the deduced theorem is illustrated by an example of optical simulation of partially coherent and partially polarized secondary source with the controlled statistical properties.

Coherent-Mode Representation of Propagation-Invariant Fields

The general coherent-mode structure of a propagation-invariant field is found as the solution of the differential equation for propagation of the coherent modes of said field. It is shown that three kinds of the propagation-invariant fields exist. Examples of propagation-invariant fields of the three kinds are discussed.

Comparing efficiency and accuracy of the kinoform and the helical axicon as Bessel–Gauss beam generators

We compare two phase optical elements that are employed to generate approximate Bessel-Gauss beams of arbitrary order. These elements are the helical axicon (HA) and the kinoform of the desired Bessel-Gauss beam. The HA generates a Bessel beam (BB) by free propagation, and the kinoform is employed in a Fourier spatial filtering optical setup. As the main result, it is obtained that the error in the BBs generated with the kinoform is smaller than the error in the beams obtained with the HA. On the other hand, it is obtained that the efficiencies of the methods are approximately 1.0 (HA) and 0.7 (kinoform).

Generation of light string and light capillary beams

Abstract Recently we reported a new modal theory of propagation-invariant optical fields [Opt. Commun. 195 (2001) 27–34]. Within the framework of this theory we predicted the existence of so-called light string and light capillary beams. Here, we propose an optical technique for generating these beams and demonstrate it through experimental results.

Effect of coherence and polarization on resolution of optical imaging system

The effect of coherence properties of illumination on image resolution, well known in a scalar case, is studied for the case of vector electromagnetic illumination. Using an example of vector Gaussian Schell-model illumination, we analyze the dependence of optical system resolution on the transverse correlation lengths of the orthogonal field components and on the ratio of the powers of these components, each taken separately.