Biomedical subjects

S A Ponomarenko

Publications and source records attributed to S A Ponomarenko.

5 recordsLinked to original sources

PubMed2004

Theory of incoherent optical solitons: beyond the mean-field approximation.

We present a general theory of partially coherent optical solitons in slow-responding nonlinear media that takes into account intensity fluctuations of the light sources generating such solitons. If intensity fluctuations of the source are negligible, the theory reduces to the previously reported mean-field theory of partially coherent solitons. However, when such fluctuations are significant, our theory shows that the properties of partially coherent solitons in saturable nonlinear media can be qualitatively different from those predicted by the mean-field theory.

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PubMed2004

Energy spectrum of a nonstationary ensemble of pulses.

We introduce a new definition of the energy spectrum of a nonstationary ensemble of pulses that reduces to the usual ones in the limit of statistically stationary ensembles of signals and of fully temporarily coherent ensembles.

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PubMed2001

Twisted Gaussian Schell-model solitons.

We show that a certain class of spatially partially coherent solitons, namely, twisted Gaussian Schell-model solitons, exists in a logarithmically saturable nonlinear medium with a noninstantaneous temporal response. Unlike previously reported Gaussian Schell-model solitons, those discussed here carry a position-dependent twist phase, which vanishes in the fully coherent limit. We demonstrate that the presence of the twist phase provides an opportunity for controlling the degree of spatial coherence of such solitons without affecting their intensity.

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PubMed2001

A class of partially coherent beams carrying optical vortices.

A new class of partially coherent beams with a separable phase, which carry optical vortices, is introduced. It is shown that any member of the class can be represented as an incoherent superposition of fully coherent Laguerre-Gauss modes of arbitrary order, with the same azimuthal mode index. The free-space propagation properties of such partially coherent beams are studied analytically, and their M2 quality factor is investigated numerically.

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PubMed1999

Spectral changes of light produced by scattering from disordered anisotropic media.

We investigate theoretically changes in the spectrum of polychromatic light scattered by a disordered, birefringent medium. We derive an expression for the spectrum of scattered light for ordinary and extraordinary incident waves within the accuracy of the first Born approximation. Using this result, we analyze the changes in the spectrum of light due to the combined action of disorder and anisotropy in the scattering process.

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