Emmanouil Skantzakis

Foundation for Research and Technology - Hellas | forth · Institute of Electronic Structure and Laser (IESL)

Studies of ultrafast dynamics along with femtosecond-pulse metrology rely on non-linear processes, induced solely by the exciting/probing pulses or the pulses to be characterized. Extension of these approaches to the extreme-ultraviolet (XUV) spectral region opens up a new, direct route to attosecond scale dynamics. Limitations in available intensi...

Continuing efforts in ultrashort pulse engineering have recently led to the breakthroughs of the generation of attosecond (10-18 s) pulse trains1, 2, 3, 4, 5, 6, 7 and isolated pulses8, 9, 10, 11. Although trains of multiple pulses can be generated through the interaction of many-optical-cycle pulses with gases—a process that has led to intense ext...

Extremely nonlinear spectroscopy based on high-order-harmonic generation has become a powerful investigation method for attosecond dynamics in gas and solid targets. In particular, the phase of harmonic emission was shown to carry profound insight into atomic and molecular structure and dynamics. However, current techniques offer phase measurements...

In this study, the generation of energetic coherent extreme ultraviolet (XUV) radiation with the potential for controlled polarization is reported. The XUV radiation results from the process of high harmonic generation (HHG) in a gas phase atomic medium, driven by an intense two-color circularly polarized counter-rotating laser field, under loose f...

In this work, we demonstrate experimentally the efficient generation and tunability of energetic highly elliptical high harmonics in Ar gas, driven by intense two-color counter-rotating laser electric fields. A bichromatic beam tailored by a Mach-Zehnder-Less for Threefold Optical Virginia spiderwort (MAZEL-TOV) apparatus generates high-order harmo...

In the present work we report on the current progress of the recently constructed GW attosecond extreme ultraviolet (XUV) source developed at the Institute of Electronic Structure and Laser of the Foundation for Research and Technology-Hellas (I.E.S.L-FO.R.T.H.). By the implementation of a compact-collinear polarization gating arrangement, the gene...

Two-XUV-photon double ionization of Ne, induced by an intense few-pulse attosecond train with a ∼4 fs envelope duration is investigated experimentally and theoretically. The experiment is performed at ELI-ALPS (Extreme Light Infrastructure Attosecond Light Pulse Source) utilizing the recently constructed 10 Hz gas phase high-order harmonic generati...

In this paper, we test the possibility to use luminescence of metal (aluminum and silver) nanoparticles (NPs), synthesized using different laser-driven ablation methods, as sensors for radiation detection. Energetic photon and electron radiation produced by intense plasma induces a red-shift in the luminescence emitted by the NPs. Observing the phe...

Two XUV-photon double ionization of Ne, induced by an intense few-pulse attosecond train with a ~ 4 fs envelope duration is investigated experimentally and theoretically. The experiment is performed at ELI-ALPS utilizing the recently constructed 10 Hz gas phase high-order harmonic generation SYLOS GHHG-COMPACT beamline. A total pulse energy up to ~...

Tunability of energetic highly-elliptical high-harmonics is demonstrated. Harmonics are generated in Ar gas, driven by intense two-color counter rotating laser electric fields, namely of the fundamental and second harmonic frequency. For the experiment a MAZEL-TOV-like device is used, combined with loose focusing geometry. By properly tuning the ce...

We measure for the first time the duration of long-quantum path EUV high harmonics produced in xenon gas. The long-quantum path contribution to the high-harmonic signal was carefully controlled by employing a two-colour driving laser field and a high-harmonic spatial selection in the far field, over a range of $18-25\,eV$ in photon energy. To chara...

In this study the generation of energetic coherent extreme ultraviolet (XUV)radiation with controlled polarization, is reported. The XUV radiation resultsfrom the process of high harmonic generation (HHG), in a gas phase atomicmedium, driven by an intense two-color circularly polarized counter-rotating laser field, under loose focusing geometry con...

Signatures of strong-field effects induced by an intense attosecond pulse train, synthesized by the superposition of a Ti:sapphire laser high-order harmonics are observed in atomic two-photon ionization. Ponderomotive shifts in the photoelectrons’ kinetic energies have been measured in the non-resonant two-photon ionization of Helium atoms induced...

Electron quantum path interferences in strongly laser-driven aligned molecules and their dependence on the molecular alignment is an essential open problem in strong-field molecular physics. Here, we demonstrate an approach which provides direct access to the observation of these interference processes. The approach is based on the combination of t...

Recent developments in extreme ultraviolet (XUV) and x-ray radiation sources have pushed pulse energies and durations to unprecedented levels that opened up the era of non-linear XUV and x-ray optics. In this quest, laser driven high order harmonic generation sources providing attosecond resolution in the XUV spectral region enabled XUV-pump-XUV-pr...

The quantum mechanical motion of electrons and nuclei in systems spatially confined to the molecular dimensions occurs on the sub-femtosecond to the femtosecond timescales respectively. Consequently, the study of ultrafast electronic and, in specific cases, nuclear dynamics requires the availability of light pulses with attosecond (asec) duration a...

Motivated by the achieved high intensities of novel extreme ultraviolet (XUV) radiation sources, such as free electron lasers and laser-driven high harmonic generation beamlines, we elaborate on their perspective in inducing observable strong field effects. The feasibility of extending such effects from the infrared and visible spectral regimes in...

Electron quantum path interferences in strongly laser-driven aligned molecules and their dependence on the molecular alignment is an essential open problem in strong-field molecular physics. Here, we demonstrate an approach which provides direct access to the observation of these interference processes. The approach is based on the combination of t...

Attoscience is the emerging field that accesses the fastest electronic processes occurring at the atomic and molecular length scales with attosecond (1 as = 10^-18s) time resolution having wide ranging physical, chemical, material science and biological applications. The quintessential and one of the most fundamental processes in this domain is the...

The long-standing scientific quest of real-time tracing electronic motion and dynamics in all states of matter has been remarkably benefited by the development of intense laser-based pulsed sources with a temporal resolution in the attosecond [1 attosecond = 10⁻¹⁸ s] time scale. Nowadays, attosecond pulses are routinely produced in laboratories by...

In this work, we introduce the use of laser-plasma driven spectroscopy as alternative to classical methods for analyzing nanomaterials, nanocomposites, insulators and semiconductors. We demonstrate that our spectroscopy, based on an In-Air Plasma-Induced Luminescence (In-Air-PIL), allows one to obtain the same information as acquired by classical p...

We introduce the use of an In-Air Plasma-Induced Luminescence (In-Air-PIL) spectroscopy as an alternative to classical chemical and crystallographic methods used in materials science. The In-Air-PIL is evaluated on a case study investigating the effect of light aging on the darkening of five pristine yellow pigments commonly used in artworks. We sh...

We report the application of the time gated ion microscopy technique in accessing online the position of the source of harmonics generated in atomic gas media. This is achieved by mapping the spatial extreme-ultraviolet (XUV)-intensity distribution of the harmonic source onto a spatial ion distribution, produced in a separate focal volume of the ge...

We report the application of the time gated ion microscopy technique in accessing online the position of the source of harmonics generated in atomic gas media. This is achieved by mapping the spatial extreme-ultraviolet (XUV)-intensity distribution of the harmonic source onto a spatial ion distribution, produced in a separate focal volume of the ge...

The present work reports on the generation of short-pulse coherent extreme ultraviolet radiation of controlled polarization. The proposed strategy is based on high-order harmonics generated in pre-aligned molecules. Field-free molecular alignment produced by a short linearly-polarized infrared laser pulse is used to break the isotropy of a gas medi...

In this paper, a new synthesis of carbon‐based nanostructured films for application as plasma facing materials during high‐intense laser‐matter interaction experiments is presented. The materials are produced using a Polyethylene glycol (PEG) matrix, nanostructured with multiwalled carbon nanotubes, or multi‐layer graphene flakes producing a 250 μm...

We report the observation of multiple ionization of argon through multi-XUV-photon absorption induced by an unprecedentedly powerful laser driven high-order harmonic generation source. Comparing the measured intensity dependence of the yield of the different argon charge states with numerical calculations we can infer the different channels—direct...

We report the observation of multiple ionization of Argon through multi-XUV-photon absorption induced by an unprecedentedly powerful laser driven high-harmonic-generation source. Comparing the measured intensity dependence of the yield of the different Argon charge states with numerical calculations we can infer the different channels -direct and s...

We present conditions, based on loose focusing geometries, which can be used for the generation of ultrahigh power XUV pulses. Preliminary data regarding the approach’s feasibility will be presented.

During the last decades, systematic efforts in ultra-short pulse generation led to the development of table-top sources with the capability of producing such pulses in the extreme-ultraviolet spectral range (XUV). Such pulses have been extensively exploited in the investigation of ultrafast dynamics in all states of matter. Intense XUV radiation, t...

This review presents the technological infrastructure that will be available at the Extreme Light Infrastructure Attosecond Light Pulse Source (ELI-ALPS) international facility. ELI-ALPS will offer to the international scientific community ultrashort pulses in the femtosecond and attosecond domain for time-resolved investigations with unprecedented...

Real-time observation of ultrafast dynamics in the microcosm is a fundamental approach for understanding the internal evolution of physical, chemical and biological systems. Tools for tracing such dynamics are flashes of light with duration comparable to or shorter than the characteristic evolution times of the system under investigation. While fem...

The present work reports on the generation of short-pulse coherent extreme ultraviolet radiation of controlled polarization. The proposed strategy is based on high-order harmonics generated in pre-aligned molecules. Field-free molecular alignment produced by a short linearly-polarized infrared laser pulse is used to break the isotropy of a gas medi...

We demonstrate a tool for quantitative measurements in the extreme ultraviolet (EUV) spectral region measuring spatially resolved atomic ionization products at the focus of an EUV beam. The ionizing radiation is a comb of the 11th–15th harmonics of a Ti:Sapphire femtosecond laser beam produced in a Xenon gas jet. The spatial ion distribution at the...

We report on high-order harmonic (HHG) two-source interferometry (TSI) in molecular gases. We used a 0-π phase plate to create two bright spots at the focus of a lens by converting a Gaussian laser beam into a TEM please define 01 Transverse Electromagnetic Mode. The two bright foci produce two synchronized HHG sources. One of them is used to probe...

Exploiting intense coherent XUV continua, supporting attosecond pulse formation, we have performed the first ever XUV-pump-XUV-probe studies of 1fs scale dynamics in atoms and molecules. Progress towards single shot non-linear XUV autocorrelation is also reported.

Attosecond pulses today are generated at pulse energies leading to intensities sufficient to induce two-photon transitions in the extreme ultraviolet (XUV) spectral region. Recently, ultra-broadband coherent XUV continua fulfill also the requirements in inducing such processes. Two-XUV-photon ionization is a pivotal tool in attosecond pulse metrolo...

We report the observation of the direct two-XUV-photon double ionization of xenon by energetic coherent XUV continuum radiation. The spectrum of the XUV continuum spans from ∼15 to ∼23 eV, for which the two-photon sequential double ionization channel is partially open. The two-XUV-photon process is exploited in a second-order autocorrelation measur...

We report (a) the observation of two-XUV-photon direct double ionization, while the two-XUV-photon sequential channel is open, (b) a second order autocorrelation of an ultra-broadband XUV continuum and (c) an XUV-pump-XUV-probe study of an induced atomic coherence with 1fs scale temporal resolution.

Real-time observation of ultrafast dynamics in all states of matter requires temporal resolution on the atomic unit of time (24.189 asec) ( 1asec = 10-18s1\,\mathrm{asec} = 1{0}^{-18}\,\mathrm{s} ). Tools for tracking such ultrafast dynamics are ultrashort light pulses. During the last decade, continuous efforts in ultrashort pulse engineering led...

We report on ultra-broadband XUV Fourier Transform spectroscopy, implemented through XUV time resolve spectroscopy of an autoionizing electron wave-packet, i.e. a coherent superposition of doubly excited and Auger decaying inner-shell excited states.

The carrier-envelope phase (CEP) of high-peak-power, many-cycle laser fields becomes a crucial parameter when such fields are used, in conjunction with polarization gating techniques, in isolated attosecond (asec) pulse generation. However, its measurement has not been achieved so far. We demonstrate a physical process sensitive to the CEP value of...

The two basic approaches underlying most of the metrology of attosecond pulse trains are compared in the spectral region {approx}14-24 eV, that is, the second-order intensity volume autocorrelation and the resolution of attosecond beating by interference of two photon transitions (RABITT). They give rather dissimilar pulse durations. It is conclude...

The emission of above-ionization-threshold harmonics results from the recombination of two electron wavepackets moving along a "short" and a "long" trajectory in the atomic continuum. Attosecond pulse train generation has so far been attributed to the short trajectory, attempted to be isolated through targeted trajectory-selective phase matching co...

We present time-resolved studies and Fourier transform spectroscopy of inner-shell excited states undergoing Auger decay and doubly excited autoionizing states, utilizing coherent extreme-ultraviolet (XUV) radiation continua. Series of states spanning a range of ∼4  eV are excited simultaneously. An XUV probe pulse tracks the oscillatory and decayi...

We present time resolved studies and Fourier-Transform-Spectroscopy of inner-shell excited states undergoing Auger decay and doubly excited autoionizing states, utilizing coherent extreme-ultraviolet (XUV) radiation continua. Series of states spanning a range of ~4eV are excited simultaneously. An XUV probe pulse tracks the oscillatory and decaying...

The two basic approaches underlying the metrology of attosecond pulse trains are compared, i.e. the 2nd order Intensity Volume Autocorrelation and the Resolution of Attosecond Beating by Interference of Two photon Transitions (RABITT). They give rather dissimilar results with respect to the measured pulse durations. It is concluded that RABITT may...

High-energy coherent continuum radiation is generated by the interaction of rare gases with a high-power many-cycle laser field, utilizing the interferometric polarization gating technique. A narrow temporal gate is formed in the laser pulse within which the extreme ultraviolet (XUV) emission is restricted. An analytical expression for the gate fun...

The authors present results on the production of high energy, in the range of multi-ten nJ, coherent continuum radiation generated by the interaction of rare gases with a high power many-cycle laser field. The emission occurs as a result of an improved IPG technique. This radiation can support intense isolated asec pulses capable to induce two-XUV-...

Talk given by D. Charalambidis

After introducing the importance of non-linear processes in the extreme-ultra-violet (XUV) spectral regime to the attosecond (asec) pulse metrology and time domain applications, we present two successfully implemented techniques with excellent prospects in generating intense asec pulse trains and isolated asec pulses, respectively. For the generati...

We demonstrate full spectral phase/amplitude distribution retrieval of an arbitrary superposition of the third and fifth harmonic fields of 800 nm central wavelength, fs laser radiation, through a cross-correlation approach. Using the retrieved distributions, the temporal profile of the total harmonic field has been reconstructed and found to be in...

The study of the laser pulse duration effect on the silicon micro-spikes morphology is presented. The microcones were produced by ultraviolet (248nm) laser irradiation of doped Si wafers in SF6 environment. The laser pulse duration was adjusted at 450fs, 5ps and 15ns. We have analyzed the statistical nature of the spikes’ morphological characterist...

Nowadays, it is well established that the superposition of higher-order harmonics (HOH), resulting from the non-linear response of matter to intense laser pulses (greater than 1013 W/cm2), comprises an avenue towards ultra-short pulse generation reaching the attosecond time-scale. Although this field has progressed significantly there are still a n...