Rostyslav Danylo

Rostyslav Danylo
École Polytechnique · Laboratoire d'Optique Appliquée (LOA)

Doctor of Philosophy

About

19
Publications
2,656
Reads
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101
Citations
Additional affiliations
March 2016 - September 2016
École Polytechnique
Position
  • Intern
Description
  • Research internship of Master 2 program on lasing effect from filaments
December 2014 - May 2015
Taras Shevchenko National University of Kyiv
Position
  • Master's Student
Description
  • Tutor practice including all types of academic classes: lectures, seminars and laboratory practice
September 2014 - November 2014
Université Paris-Sud 11
Position
  • Intern
Description
  • Internship on development of highly-stable CW lasers
Education
September 2016 - December 2019
École Polytechnique
Field of study
  • Optics and Photonics
September 2015 - September 2016
Université du Maine
Field of study
  • Physics and Optical Engineering
September 2013 - June 2015
Taras Shevchenko National University of Kyiv
Field of study
  • Physics

Publications

Publications (19)
Preprint
Full-text available
Quantum interference occurs frequently in the interaction of laser radiation with materials, leading to a series of fascinating effects such as lasing without inversion, electromagnetically induced transparency, Fano resonance, etc. Such quantum interference effects are mostly enabled by single-photon resonance with transitions in the matter, regar...
Article
We present a model describing ionization and excitation of nitrogen molecules by a strong and short laser pulse. Different from previous publications, both processes are considered within the same formalism of the density matrix. We account for the dependence of the dipole moment on the vibrational quantum number and for a large number of excited l...
Article
Full-text available
Delayed cavity-free forward lasing at the wavelengths of 391 and 428 nm was observed in recent experiments in air or pure nitrogen pumped with an intense femtosecond laser pulse at wavelength of 800 nm. The mechanism responsible for the lasing is highly controversial. In this article we propose a model explaining the delayed lasing, which contains...
Article
The time profile of a lasing signal at 391.4 nm emitted by a weakly ionized gas of nitrogen molecules at low pressure is measured under double excitation with intense femtosecond laser pulses at 800 nm. An abrupt decrease in emission occurs at the time of arrival of the second pulse. It is explained by a transfer of population from ground to first...
Article
Full-text available
Cavity-free lasing of N2+ induced by a femtosecond laser pulse at 800 nm is nearly totally suppressed by a delayed twin control pulse. We explain this surprising effect within the V-scheme of lasing without population inversion. A fast transfer of population between nitrogen ionic states X2Σg+ and A2Πu, induced by the second pulse, terminates the c...
Preprint
Full-text available
Cavity-free lasing of N$_2^+$ induced by a femtosecond laser pulse at 800~nm is nearly totally suppressed by a delayed twin pump pulse. We explain this surprising effect within the V-scheme of lasing without population inversion. A fast transfer of population between nitrogen ionic states X$^2\Sigma_g^+$ and A$^2\Pi_u$, induced by the second pulse,...
Preprint
Full-text available
Delayed cavity-free forward lasing at the wavelengths of 391 and 428 nm was observed in recent experiments in air or pure nitrogen pumped with an intense femtosecond laser pulse at wavelength of 800~nm. The mechanism responsible for the lasing is highly controversial. In this article we explain the delayed emission by the presence of long-lived pol...
Article
Full-text available
We report on the observation of backward lasing at 391.4 nm of nitrogen ions pumped by linearly polarized intense femtosecond pulses at 800 nm. The strongly enhanced spectral intensity at 391.4 nm, as well as the amplification of an externally injected backward seeding pulse, confirm that the backward 391.4 nm signal is due to optical amplification...
Article
Nitrogen molecules are promoted to excited neutral states during femtosecond laser pulse filamentary propagation in atmosphere, leading to a characteristic UV fluorescence. Using a laser-induced fluorescence depletion technique, we measure the formation dynamics of these excited neutral nitrogen molecules with femtosecond time resolution. We find t...
Article
Full-text available
We experimentally demonstrate the existence of long-lived coherent polarizations coupling simultaneously ground state X (X2Σg+) to excited states A (A2Πu) and B (B2Σu+) of N2+ inside a plasma created by a short intense laser pulse at 800 nm. This three-level V-scheme arrangement is responsible for a strong optical gain without population inversion...
Conference Paper
Full-text available
We attribute the mechanism of “lasing” action of nitrogen ions pumped by femtosecond IR pulses to a laser without inversion scheme. Numerical simulations reproduce well the temporal dynamics and pressure dependence of the emission.
Preprint
Full-text available
A cavity-free laser in the sky could lead to revolutionary improvements in optical remote sensing for atmospheric science. Abundant in air, nitrogen molecules are prime candidates as an active medium for such a laser. Nitrogen molecules, either neutral or singly ionized, exhibit a significant optical gain in the UV regime when pumped by an intense...
Conference Paper
Full-text available
Air pumped by mid-infrared femtosecond pulses gives rise to coherent emission at 391 nm. Based on ellipticity dependence measurement and time-resolved characterization, we attribute this emission to resonance-enhanced harmonics in perturbative regime.
Conference Paper
Air pumped by mid-infrared femtosecond pulses gives rise to coherent emission at 391/428 nm. Based on ellipticity dependence measurement and time-resolved characterization, we attribute this emission to resonance-enhanced low order harmonics.
Article
Full-text available
Nitrogen molecules in ambient air exposed to an intense near-infrared femtosecond laser pulse give rise to cavity-free superradiant emission at 391.4 and 427.8 nm. An unexpected pulse duration-dependent cyclic variation of the superradiance intensity is observed when the central wavelength of the femtosecond pump laser pulse is finely tuned between...
Article
Hydrogen bonds and their fluctuations are one of the factors that determine the unique properties of water [1]. Building models of formation and rupture of hydrogen bonds due to non-eigen vibrations of a molecule of water is to a large extent determined by the availability of accurate information on the geometric structure of the water molecule. Ge...
Article
This research is devoted to the vibrational spectroscopy inverse problem solution that gives a possibility to design a molecule and make conclusions about its geometry. The valence angle finding based on the usage of inverse spectral vibrational spectroscopy problem is a well-known task. 3N-matrix method was chosen to solve the proposed task. The u...

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Projects

Project (1)
Project
Air turns into an optically amplifying medium under excitation by intense ultra-short laser pulses. This free-space “air lasing” is potentially capable of generating backward and forward laser radiation remotely in the sky, and revolutionize the current technique of remote sensing in atmosphere. Ours goals: - clarify the fundamental mechanisms involved in the lasing actions of neutral nitrogen molecule and nitrogen molecular ions. - search for the optimal operational conditions for the backward nitrogen laser and improve its properties such as pulse energy and divergence for future applications.