S. Orlov

Propagation of Bessel beams carrying optical vortices

The variation of the vorticity of the superposition of two Bessel singular beams under free-space propagation is analyzed. We demonstrate that in the near field the combined beam creates light pattern with much richer vortex content than that of individual beams. Under diffraction the combined beam dynamically evolves into the beam with rather simple vortical structure in the far field. A qualitative agreement of experimental results with theoretical predictions is obtained.

Focus wave modes in optical parametric generators

It is shown that in the paraxial approximation the conditions for noncollinear phase matching for three-wave parametric interaction in a nonlinear crystal coincide with the conditions for generation of focus wave modes. As a result, the creation of broadband localized optical fields (pulsed beams without diffraction and dispersion spreading) inside the crystals of parametric generators is feasible.

Localized optical subcycle pulses in dispersive media

The conditions for creation of broadband localized optical fields (Bessel X pulses and focus wave modes) in dispersive media are analyzed. It is shown that transmission of focus wave modes with subcycle pulse durations through fused silica is possible.

Parametric excitation of X-waves by downconversion of Bessel beams in nonlinear crystals.

We predict that in traveling-wave degenerate parametric downconversion the Bessel beam pump stimulates the appearance of a nondiffracting X-wave from quantum noise amplification. Numerical simulation results of downconversion in ADP crystal are presented, along with preliminary experimental data.

Free-space propagation of second harmonic beams carrying optical vortices

Abstract A vorticity of free propagating SH beam produced in nonlinear crystal by combined beam composed of two coaxial Laguerre–Gaussian vortex beams is analyzed. It is revealed that the vortical structures of SH beam in the near and far fields are different when two vortex beams are carrying vortices with topological charges of different signs. The diffraction of SH beam under free propagation is investigated. A qualitative agreement of the theoretical predictions with experimental results is obtained.

Excitation of X-waves by downconversion of Bessel beam in optical parametric amplifier

An appearance of nondiffracting X-waves from quantum noise parametric amplification by the Bessel beam pump is investigated. The numerical simulation results in ADP crystal and preliminary experimental data are presented.

Phase matching of X-waves in nonlinear crystals

The phase-matching conditions of interacting optical X waves in /spl chi//sup 2/ crystals are obtained. It is demonstrated experimentally that angular dispersion of the waves excited in optical parametric generator corresponds to angular dispersion of nondiffracting pulsed beams.

Phase matching of X-waves

This paper demonstrates a comprehensive analysis of phase-matching conditions of X-waves in various nonlinear optical processes. The single pulse (70 ps-duration) of the fourth harmonic of Nd:YAG cw-mode-locked laser is used as a pump beam of KDP crystal (type I phase-matching) based OPG. The angular frequency distribution of parametric superfluorescence is analyzed experimentally and good agreement of theoretical predictions with experimental results is obtained. This study also presents angular-frequency distribution of OPG output radiation in the air for different KDP crystal temperatures. Results show that angular dispersion of parametrically excited waves corresponds to angular dispersion of nondiffracting pulsed beams. The numerical fitting of experimental curve at degeneracy is also presented. So, the parametric downconversion of pump wave stimulates an excitation from quantum noise level the nondiffracting pulsed beams. Hence, these beams will obtain a typical X-shape if the components of spatial-temporal spectrum are phased. The appearance of conical emission in nonlinear optical process can be considered as a feature of the formation of nondiffracting waves.

Subcycle pulses of optical X waves in linear and nonlinear dispersive media

Experimental achievements of localized optical pulsed beams (Bessel X pulses and FWMs) in free space and in dispersive medium are demonstrated in practical setups. Further, this study reveals the possibilities of creating broadband optical localized pulsed beams with subcycle pulse durations in linear and nonlinear dispersive media.