Mr. Máté Kovács Profile

Máté Kovács

at ELI-HU Nonprofit Kft

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Publications (5)

Proceedings Article | 14 March 2018 Presentation

Relativistic-intensity near-single-cycle laser system at 1 kHz (Conference Presentation)

Frederik Böhle, Andreas Blumenstein, Maïmouna Bocoum, Aline Vernier, Magali Lozano, Jean-Philippe Rousseau, Aurélie Jullien, Dominykas Gustas, Diego Guénot, Jérôme Faure, Máté Kovács, Martin Kretschmar, Peter Simon, Uwe Morgner, Tamás Nagy, Rodrigo López-Martens

Proceedings Volume 10511, 105111A (2018) https://doi.org/10.1117/12.2289088

KEYWORDS: Plasma, Extreme ultraviolet, Mirrors, Pulsed laser operation, Laser systems engineering, Femtosecond phenomena, Ultrafast phenomena, Waveguides, Capillaries, Fiber lasers

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Proceedings Article | 15 February 2018 Presentation + Paper

Measurement of the dispersion properties of large aperture mirrors at arbitrary incidence angle and polarization state

M. Kovacs, T. Somoskoi, I. Seres, A. Borzsonyi, A. Sipos

Proceedings Volume 10525, 105250B (2018) https://doi.org/10.1117/12.2289695

KEYWORDS: Mirrors, Interferometers, Polarization, Light sources, Interferometry, Infrared spectroscopy, Spectroscopy, Lamps, Refractive index, Beam splitters

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Proceedings Article | 9 June 2017 Presentation

Performance tests of the 5 TW, 1 kHz, passively CEP-stabilized ELI-ALPS SYLOS few-cycle laser system (Conference Presentation)

Tomas Stanislauskas, Rimantas Budriūnas, Gediminas Veitas, Darius Gadonas, Jonas Adamonis, Aidas Aleknavičius, Gžegož Masian, Zenonas Kuprionis, Dominik Hoff, Gerhard Paulus, Ádám Börzsönyi, Szabolcs Toth, Mate Kovacs, János Csontos, Rodrigo López-Martens, Károly Osvay

Proceedings Volume 10238, 102380S (2017) https://doi.org/10.1117/12.2265775

KEYWORDS: Laser systems engineering, Plasma systems, Reliability, Picosecond phenomena, Light, Light sources, Plasma, Laser applications, Standards development, Glasses

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ELI-ALPS in Hungary, one of the three pillars of the Extreme Light Infrastructure, aims at providing diverse light sources, including energetic attosecond pulses at the highest possible repetition rates. One of the main laser systems for driving plasma and gas-based HHG stages, is a state-of-the-art 1 kHz few-cycle laser called SYLOS. Targeted pulse parameters are an energy of 100 mJ and a duration shorter than two optical cycles (<6 fs), with outstanding energy, phase and pointing stability as well as high spatiotemporal quality. The first phase of the laser system has already set a new standard in kHz laser system engineering and technology. The performance and reliability of the SYLOS laser have been consistently tested over the course of a six-month trial period. During this time the system was running at least 8 hours a day at full power for more than 5 months. The current output parameters are 5 TW peak power, 45 mJ pulse energy with 9 fs duration and 300 mrad CEP stability, while the spectrum spans over 300 nm around 840 nm central wavelength. The layout follows the general scheme NOPCPA architecture with a passively CEP-stabilized front-end. The pulses are negatively chirped for the amplification process and compressed by a combination of large aperture bulk glass blocks and positively chirped mirrors under vacuum conditions at the output. During the trial period, the laser system demonstrated outstanding reliability. Daily startup and shutdown procedures take only a few minutes, and the command-control system enables pulse parameters to be modified instantly. Controlling the delays of individual NOPCPA stages makes it possible to tailor the output spectrum of the pulses and tune the central wavelength between 770 nm and 940 nm. We performed several experimental tests to find out the pulse characteristics. Pulse duration was verified with Wizzler, chirp-scan, autocorrelation methods and a stereo-ATI independently. All of them confirmed the sub-9 fs pulse duration. We recorded the long-term waveform and pointing stabilities of the beam in order to find out the effect of the temperature load on optical elements. Excluding a short initial warm up time, stable signals were observed in general. The in-loop and out-of-loop CEP stability was cross-checked between f-to-2f and stereo-ATI devices. Moreover, the inherent CEP stability of the system without feedback loop was also found to be surprisingly robust thanks to the passive CEP stabilization of the front-end. The polarization contrast was better than 1000:1. The temporal contrast was also measured independently with Sequoia and Tundra cross-correlators, and on the ns scale with a fast photodiode and GHz oscilloscope as well. Results showed that the pulse pedestal generally consists of parametric superfluorescence below the 1E-7 level and about 100 ps long, well in accordance with the pump duration. Delaying the pump pulse allows us to shift the seed pulse to the front and reach a pre-pulse pedestal below 1E-11 at 30 ps before the pulse peak. Detailed findings on all the examined pulse characteristics of the SYLOS laser will be reported in this presentation.

Proceedings Article | 9 June 2017 Presentation

TW-class hollow-fiber compressor with tunable pulse duration (Conference Presentation)

Frederik Boehle, Aline Vernier, Martin Kretschmar, Aurélie Jullien, Mate Kovacs, Rosa Romero, Helder Crespo, Peter Simon, Tamas Nagy, Rodrigo Lopez-Martens

Proceedings Volume 10238, 102380R (2017) https://doi.org/10.1117/12.2265679

KEYWORDS: Plasma, Mirrors, Lanthanum, Optical spheres, Photonics, Ultrafast phenomena, High power lasers, Multiplexing, Waveguides, Capillaries

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CEP-stable few-cycle light pulses find numerous applications in attosecond science, most notably the production of isolated attosecond pulses for studying ultrafast electronic processes in matter [1]. Scaling up the pulse energy of few-cycle pulses could extend the scope of applications to even higher intensity processes, such as attosecond dynamics of relativistic plasma mirrors [2]. Hollow fiber compressors are widely used to produce few-cycle pulses with excellent spatiotemporal quality [3], where octave-spanning broadened spectra can be temporally compressed to sub-2-cycle duration [4,5]. Several tricks help increase the output energy: using circularly polarized light [6], applying a pressure gradient along the fiber [7] or even temporal multiplexing [8]. The highest pulse energy of 5 mJ at 5 fs pulse duration was achieved by using a hollow fiber in pressure gradient mode [9] but in this case no CEP stabilization was achieved, which is crucial for most applications of few-cycle pulses. Nevertheless, it did show that in order to scale up the peak power, the effective length and area mode of the fiber had to be increased proportionally, thereby requiring the use of longer waveguides with larger apertures. Thanks to an innovative design utilizing stretched flexible capillaries [10], we recently demonstrated the generation CEP-stable sub-4fs pulses with 3mJ energy using a 2m length 450mm bore hollow fiber in pressure gradient mode [11]. Here, we show that a stretched hollow-fiber compressor operated in pressure gradient mode can generate relativistic intensity pulses with continuously tunable waveform down to almost a single cycle (3.5fs at 750nm central wavelength). The pulses are characterized online using an integrated d-scan device directly under vacuum [12]. While the pulse shape is tuned, all other pulse characteristics, such as energy, pointing stability and focal distribution remain the same on target, making it possible to explore the dynamics of plasma mirrors using controllable relativistic-intensity light waveforms at 1kHz. [1] Krausz and Ivanov, Rev. Mod. Phys. 81, 163 (2009). [2] Borot et al., Nature Phys. 8, 417-421 (2012). [3] Nisoli et al., Appl. Phys. Lett. 68, 2793–2795 (1996).   [4] Park et al., Opt. Lett. 34, 2342–2344 (2009). [5] Schweinberger et al., Opt. Lett. 37, 3573–5 (2012). [6] Chen et al., Opt. Lett. 34, 1588–1590 (2009). [7] Suda et al., Appl. Phys. Lett. 86, 111116 (2005). [8] Jacqmin et al., Opt. Lett. 40, 709-712 (2015) [9] Bohman et al., Opt. Lett. 35, 1887–9 (2010). [10] Nagy et al., Appl. Opt. 47, 3264–3268 (2008). [11] Boehle et al., Las. Phys. Lett. 11, 095401 (2014). [12] Miranda et al., Opt. Express 20, 18732-43 (2012)

Proceedings Article | 9 June 2017 Presentation

Dispersion measurement on chirped mirrors at arbitrary incidence angle and polarization state (Conference Presentation)

Mate Kovacs, Tamas Somoskoi, Imre Seres, Adam Borzsonyi, Aron Sipos, Károly Osvay

Proceedings Volume 10238, 102380A (2017) https://doi.org/10.1117/12.2265692

KEYWORDS: Mirrors, Polarization, Interferometers, Infrared spectroscopy, Spectroscopy, Optical components, Femtosecond phenomena, Ultrafast phenomena, Glasses, Nonlinear optical glasses

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The optical elements of femtosecond high peak power lasers have to fulfill more and more strict requirements in order to support pulses with high intensity and broad spectrum. In most cases chirped pulse amplification scheme is used to generate high peak power ultrashort laser pulses, where a very precise control of spectral intensity and spectral phase is required in reaching transform-limited temporal shape at the output. In the case of few cycle regime, the conventional bulk glass, prism-, grating- and their combination based compressors are not sufficient anymore, due to undesirable nonlinear effects in their material and proneness to optical damages. The chirped mirrors are also commonly used to complete the compression after a beam transport system just before the target. Moreover, the manufacturing technology requires quality checks right after production and over the lifetime of the mirror as well, since undesired deposition on the surface can lead alteration from the designed value over a large part of the aperture. For the high harmonic generation, polarization gating technology is used to generate single attosecond pulses [1]. In this case the pulse to be compressed has various polarization state falling to the chirped mirrors. For this reason, it is crucial to measure the dispersion of the mirrors for the different polarization states. In this presentation we demonstrate a simple technique to measure the dispersion of arbitrary mirror at angles of incidence from 0 to 55 degree, even for a 12” optics. A large aperture 4” mirror has been scanned over with micrometer accuracy and the dispersion property through the surface has been investigated with a stable interference fringes in that robust geometry. We used Spectrally Resolved Interferometry, which is based on a Michaelson interferometer and a combined visible and infrared spectrometer. Tungsten halogen lamp with 10 mW coupled optical power was used as a white-light source so with the selected spectrometer we could investigate over the 500-1300 nm spectral range. We also measured the mirrors with broadband oscillator pulses, and we found that the dispersion was the same for both light source. Group Delay Dispersion was obtained with a ±2 fs^2 accuracy from the Fourier Transform method of the interference fringes. Using an adjunct mirror, we made possible to change continuously the angle of incidence at the chirped mirror within 3 and 55°. On the input part of the interferometer we placed a wire-grid polarizer, and sensitivity of the chirp mirrors to the polarization state have been measured at different incidence angles. To present the flexibility of the device we scanned two different compressor mirrors with +100 fs^2 and -500 fs^2 at the 800 nm central wavelength. We separately developed an optical arrangement to detect Group Delay shift between s and p polarization reflections of large aperture chirped compressor mirrors and we found that it’s below the detection limit, so further investigation will be necessary. 1. M. Ivanov, P. B. Corkum, T. Zuo, and A. Bandrauk, Routes to Control of Intense-Field Atomic Polarizability, Phys. Rev. Lett. 74, 1995

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