Shalva Amiranashvili

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The concept of rogue waves arises from a mysterious and potentially calamitous phenomenon of oceanic surfaces. There is mounting evidence that they are actually commonplace in a variety of different physical settings. A set of defining criteria has been advanced; this set is of great generality and therefore applicable to a wide class of systems. The(More)
Ultrashort pulses contain only a few optical cycles and exhibit broad spectra. Their carrier frequency is therefore not well defined and their description in terms of the standard slowly varying envelope approximation (SVEA) becomes questionable. Existing modeling approaches can be divided in two classes, namely generalized envelope equations, that stem(More)
A novel adjustable adiabatic soliton compression scheme is presented, enabling a coherent pulse source with pedestal-free, few-cycle pulses in the infrared or midinfrared regime. This scheme relies on interaction of a dispersive wave and a soliton copropagating at nearly identical group velocities in a fiber with enhanced infrared transmission. The(More)
We report on the stable cancellation of the soliton self-frequency shift (SSFS) in nonlinear optical fibers. A soliton, which scatters a group velocity matched pump wave in a so-called optical event horizon regime, may experience a blueshift in frequency, which counteracts the SSFS induced by Raman scattering. The SSFS can easily be compensated by a(More)
We review recent achievements in theory of ultra-short optical pulses propagating in nonlinear fibers. The following problem is especially emphasized: what is the shortest duration (the highest peak power) of an optical soliton and which physical phenomenon is responsible for breakdown of too short pulses. We argue that there is an universal mechanism that(More)
A possibility to control an optical soliton by a much weaker second pulse that is scattered on the soliton attracted considerable attention recently. An important problem here is to quantify the small range of parameters at which the interaction takes place. This has been achived by using adiabatic ODEs for the soliton characteristics, which is much faster(More)
We study how an optical fiber soliton can be manipulated and compressed by interactions with a properly prepared group velocity matched pump wave (waves). The pump wave is scattered at the soliton, which is then accelerated, compressed, and may even reach a nearly single-cycle regime. Unfortunately, the pump wave scattering is efficient only in a narrow(More)
A new scheme for supercontinuum generation covering more than one octave and exhibiting extraordinary high coherence properties has recently been proposed [Phys. Rev. Lett. 110, 233901 (2013)]. The scheme is based on two-pulse collision at a group velocity horizon between a dispersive wave and a soliton. Here we demonstrate that the same scheme can be(More)
We consider propagation of ultrashort optical pulses in nonlinear fibers and suggest a new theoretical framework for description of pulse dynamics and exact characterization of solitary solutions. Our approach deals with a proper complex generalization of the nonlinear Maxwell equations and completely avoids the use of the slowly varying envelope(More)