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Dive into the research topics where Julia M. Mikhailova is active.

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Featured researches published by Julia M. Mikhailova.


Optics Letters | 2011

Ultra-high-contrast few-cycle pulses for multipetawatt-class laser technology.

Julia M. Mikhailova; Alexander Buck; Antonin Borot; Karl Schmid; Christopher M. S. Sears; George D. Tsakiris; Ferenc Krausz; Laszlo Veisz

We report the generation of few-cycle multiterawatt light pulses with a temporal contrast of 10(10), when measured as close as 2 ps to the pulses peak. Tens of picoseconds before the main pulse, the contrast value is expected to spread much beyond the measurement limit. Separate measurements of contrast improvement factors at different stages of the laser system indicate that real contrast values may reach 10(19) and 10(14), when measured 50 and 25 ps before the pulses peak, respectively. The combination of the shortest pulse duration and the highest contrast renders our system a promising front-end architecture for future multipetawatt laser facilities.


Physics of Plasmas | 2015

The efficiency of Raman amplification in the wavebreaking regime

Matthew R. Edwards; Zeev Toroker; Julia M. Mikhailova; Nathaniel J. Fisch

We compare previous analytic predictions, Vlasov-Maxwell simulations, and particle-in-cell results with a new set of comprehensive one and two dimensional particle-in-cell simulations in an effort to clarify apparent discrepancies between the predictions of different models for the efficiency of Raman amplification in the wavebreaking regime. We find reasonable agreement between our particle-in-cell simulations and previous results from Vlasov-Maxwell simulations and analytic work, suggesting a monotonic decrease in conversion efficiency for increased pump intensities past the wavebreaking threshold.


Optics Letters | 2014

Post-filament self-trapping of ultrashort laser pulses.

A. V. Mitrofanov; A. A. Voronin; D. A. Sidorov-Biryukov; Giedrius Andriukaitis; Tobias Flöry; A. Pugžlys; A. B. Fedotov; Julia M. Mikhailova; V. Ya. Panchenko; Andrius Baltuška; Aleksei M. Zheltikov

Laser filamentation is understood to be self-channeling of intense ultrashort laser pulses achieved when the self-focusing because of the Kerr nonlinearity is balanced by ionization-induced defocusing. Here, we show that, right behind the ionized region of a laser filament, ultrashort laser pulses can couple into a much longer light channel, where a stable self-guiding spatial mode is sustained by the saturable self-focusing nonlinearity. In the limiting regime of negligibly low ionization, this post-filamentation beam dynamics converges to a large-scale beam self-trapping scenario known since the pioneering work on saturable self-focusing nonlinearities.


Optics Letters | 2014

Enhanced attosecond bursts of relativistic high-order harmonics driven by two-color fields

Matthew R. Edwards; Victor T. Platonenko; Julia M. Mikhailova

We study the generation of attosecond x-ray and ultraviolet pulses from relativistically driven overdense plasma targets with two-color incident light. Particle-in-cell simulations show that significant improvement in pulse intensity and isolation is achievable with appropriate laser and plasma parameters. Conversion of 5% of incident laser energy to its second harmonic can enhance the intensity of generated attosecond pulses by an order of magnitude. This approach allows the generation of higher attosecond pulse intensities with existing experimental laser technology and offers a powerful tool for the analysis of the dynamics of relativistic laser-plasma interaction.


New Journal of Physics | 2011

Entanglement of biphoton states: qutrits and ququarts

M. V. Fedorov; P. A. Volkov; Julia M. Mikhailova; Stanislav Straupe; S. P. Kulik

We investigate, in a general form, entanglement of biphoton qutrits and ququarts, i.e. states formed in the processes of, correspondingly, degenerate and non-degenerate spontaneous parametric down-conversion. Indistinguishability of photons and, for ququarts, joint presence of the frequency and polarization entanglement are fully taken into account. In the case of qutrits, the most general three-parametric families of maximally entangled and non- entangled states are found, and anticorrelation of the degree of entanglement and polarization is shown to occur and to be characterized by a rather simple formula. Biphoton ququarts are shown to be two-qudits with the single-photon Hilbert space dimensionality d = 4, which differentiates them significantly from the often used two-qubit model (d = 2). New expressions for entanglement quantifiers of biphoton ququarts are derived and discussed. Rather simple procedures for a direct measurement of the degree of entanglement are described for both qutrits and ququarts.


Physics of Plasmas | 2016

Short-pulse amplification by strongly coupled stimulated Brillouin scattering

Matthew R. Edwards; Qing Jia; Julia M. Mikhailova; Nathaniel J. Fisch

We examine the feasibility of strongly coupled stimulated Brillouin scattering as a mechanism for the plasma-based amplification of sub-picosecond pulses. In particular, we use fluid theory and particle-in-cell simulations to compare the relative advantages of Raman and Brillouin amplification over a broad range of achievable parameters.


Physics of Plasmas | 2016

Distinguishing Raman from strongly coupled Brillouin amplification for short pulses

Qing Jia; Ido Barth; Matthew R. Edwards; Julia M. Mikhailova; Nathaniel J. Fisch

Plasma-based amplification by strongly coupled Brillouin scattering has recently been suggested for the compression of a short seed laser to ultrahigh intensities in sub-quarter-critical-density plasmas. However, by employing detailed spectral analysis of particle-in-cell simulations in the same parameter regime, we demonstrate that, in fact, Raman backscattering amplification is responsible for the growth and compression of the high-intensity, leading spike, where most of the energy compression occurs, while the ion mode only affects the low-intensity tail of the amplified pulse. The critical role of the initial seed shape is identified. A number of subtleties in the numerical simulations are also pointed out.


Physical Review Letters | 2016

Strongly Enhanced Stimulated Brillouin Backscattering in an Electron-Positron Plasma.

Matthew R. Edwards; Nathaniel J. Fisch; Julia M. Mikhailova

Stimulated Brillouin backscattering of light is shown to be drastically enhanced in electron-positron plasmas, in contrast to the suppression of stimulated Raman scattering. A generalized theory of three-wave coupling between electromagnetic and plasma waves in two-species plasmas with arbitrary mass ratios, confirmed with a comprehensive set of particle-in-cell simulations, reveals violations of commonly held assumptions about the behavior of electron-positron plasmas. Specifically, in the electron-positron limit three-wave parametric interaction between light and the plasma acoustic wave can occur, and the acoustic wave phase velocity differs from its usually assumed value.


conference on lasers and electro optics | 2013

Generation and applications of sub-5-fs multi-10-TW light pulses

Laszlo Veisz; D. Rivas; Gilad Marcus; Xun Gu; D. Cardenas; Julia M. Mikhailova; Alexander Buck; Tibor Wittmann; Christopher M. S. Sears; Shao-Wei Chou; Jiancai Xu; G. Ma; Daniel Herrmann; Olga Razskazovskaya; V. Pervak; Ferenc Krausz

We report on the development and relevant characteristics of an optical parametric synthesizer light source delivering sub-5-fs pulses with 80 mJ energy. The first applications of the system are attosecond and relativistic laser-plasma physics.


Optics Letters | 2013

Pulse compression to subcycle field waveforms with split-dispersion cascaded hollow fibers

A. A. Voronin; Julia M. Mikhailova; Martin Gorjan; Zsuzsanna Major; Aleksei M. Zheltikov

Carefully dispersion- and nonlinearity-managed cascades of gas-filled hollow-core fibers enable, as our theoretical analysis shows, efficient pulse compression with ultrahigh compression ratios. With dispersion and nonlinearity of individual fibers in such cascades optimized toward distinctly different goal functions, millijoule picosecond laser pulses can be compressed to sub-100-GW subcycle field waveforms.

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Karl Schmid

University of Hohenheim

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