The presentation is divided into two parts:

Introduction to Laser Physics and Short Pulse Amplification – Tyler Green

This lecture aims to give an overview of the basic principles of the core elements of chirped pulse amplifier laser systems. This begins with a discussion of laser oscillators and the generation of ultra-short pulses via modelocked oscillators. This is followed by a review of methods of temporal dispersion management and their use in pulse stretchers and compressors. 

Introduction to Laser Amplifiers – Robert Boge

In this lecture, different types and geometries of laser amplifiers are introduced. Then, we see how these building blocks and those introduced in the previous lecture form large complex laser systems. Finally, a specific example is given on how to model, design, and build a thin-disk-based multipass amplifier.

Observing fast phenomena in time time-resolved manner and controlling the outcome of such things were always at the center of research. As technology developed, we improved from millisecond temporal resolution through micro, nano, and picosecond resolution up to femtosecond by the ’90s. Electron transitions within matter happen on an even shorter time scale, in attoseconds. In 2023 the Nobel committee honored the founders of atto science with their prize, recognizing the importance of this research.

In this lecture, we will guide the audience through the technology and the challenges behind generating attosecond pulses focusing on four different ways to generate such radiation: gas, bulk, solid high harmonic generation, and XFELs. Furthermore, we give you an insight into ELI-ALPS, the facility that puts the investigation of ultrafast phenomena at the forefront of its research.

Students will get acquainted with the physical principles of the generation of short-wavelength radiation from laser-matter interaction and some selected applications of these sources. After the definition of principal quantities and description of the interaction of a bound electron with low frequency field, the principles of high-order harmonic generation and generation of single attosecond pulses will be explained, followed by plasma-based x-ray lasers and radiation from hot plasma and so-called K-alpha X-ray sources. The last part of the lecture will focus on the generation of hard X-rays from relativistic electron beams accelerated by a laser via betatron oscillations or inverse Compton scattering.

X-ray spectroscopy is a powerful tool demanded across multiple communities as it allows for tracing of structural dynamics [1], detection of electronic structure changes in chemical compounds [2], heritage studies [3] etc. This demand in the user community has led to a development of an X-ray spectroscopy station at ELI Beamlines.

ELI Beamlines is a part of the European Extreme Light Infrastructure Consortium, the world’s largest infrastructure focused on the development and use of high power lasers. Its X-ray spectroscopy station utilizes a laser-driven Cu-tape and water-jet plasma X-ray sources (PXS) with the ultimate goal to perform pump-probe experiments with the inherent pulse synchronization, due to the use of the same laser for the system excitation and feeding the PXS source. In-house built L1 Allegra is the laser of choice [4], with 15 fs pulse energy and 1 kHz repetition rate. The station is built in a von Hamos geometry and automated to a large degree.

As the pump-probe experiments are planned to be conducted at a high repetition rate, a specific care is taken of the development of sample delivery system with an appropriate sample circulation so that every new pulse meets a fresh sample portion.

Thus, in the talk I will focus on the state-of-the-art of the X-ray spectroscopy in general and at ELI Beamlines in particular, describe our status and progress in sample systems, notably including liquid samples as well as talk about the X-ray sources used for the X-ray spectroscopy.

References:

[1] M. Naumova et al., Structural dynamics upon photoexcitation-induced charge transfer in a dicopper(i)-disulfide complex. Phys.Chem.Chem.Phys., 2018, 20,6274

[2] A. Zymaková et al., X-ray spectroscopy station for sample characterization at ELI Beamlines. Sci. Rep., 2023, 13, 17258

[3] A. Zymaková et al., A fast-integrated x-ray emission spectrometer dedicated to the investigation of Pt presence in gold Celtic coins 3rd-1st century BCE). X-ray spectrometry, 2023, 52(6), 401-411

[4] A. Zymaková et al., First experiments with a water-jet plasma X-ray source driven by the novel high-power-high-repetition rateL1 Allegra laser at ELI Beamlines. J. Synchrotron Rad., 2021, 28, 1778-1785

This lecture gives an overview of the structure, functionality, and evolution of the collection control systems at ELI-ALPS. The development of the research facility as a whole created a unique environment in which a number of factors influenced the development and integration of the control system as well. Among these factors are the heterogeneous nature of the research equipment, the continuously evolving requirements, and the wide spectrum of technologies and solutions found in third-party subsystems. We outline a systematic method for the analysis and design that addresses the key issues and enables to organize the control system in way that conforms to modern software development principles. Additionally, the most important aspects of scientific data management will be highlighted with connections to control system operations.

In this lecture, the E1 experimental hall of the ELI Beamlines facility is introduced together with its support labs for sample preparation, research and development, and complementary experiments. The objective of these facilities is to provide the international user community access to state-of-the-art experimental stations for research into the structure, dynamics, and function of samples ranging from isolated atoms to complex biological samples and the solid state. To this end, ultrashort pulses from laser-driven XUV, X-ray, and particle sources are used, as well as pulses from the primary infrared lasers. A key advantage of the ELI Beamlines facility is the possibility to utilize unique combinations of lasers and laser-driven sources with near-perfect synchronization. This makes it possible to carry out demanding pump-probe experiments, aiming at understanding the complex dynamics underpinning advanced functions or fundamental processes. Researchers study the mechanisms of physical, chemical, and biological processes at the atomic level and on time scales ranging from femto- to milliseconds, study and control electronic processes, and study complex systems in a range of environments. Central experimental technologies include time-resolved optical (IR to DUV), XUV and X-ray spectroscopy, ion and electron spectroscopy and imaging as well as X-ray and XUV diffraction, scattering, imaging, and sub-picosecond pulse radiolysis. The laser facilities and beamlines are also widely used for secondary source development.

Femtosecond laser pulses find their application not only in the field of high-energy physics but also in molecular biophysics. Almost all life on Earth receives its energy and entropy from light. In addition to that light is sensed by organisms for various purposes. Femtosecond laser spectroscopy allows studying photobiology at a fundamental level and resolving molecular mechanisms underlying those reactions. Among well-understood processes, we can find photo isomerization of retinal (such as the one that takes place in human vision) and energy transfer in the light-harvesting antenna of various photosynthetic organisms. It will be explained how pump-probe experiments can be used to resolve the dynamics of photo-biological processes and how time-resolved vibration spectroscopy can be used to resolve changes on the level of individual chemical bonds.

Laser-plasma interaction has been a focal point of scientific exploration since the emergence of high-power laser technology in the 1960s. Spanning from long-pulse (ns) and high-energy (> 500 J) to short-pulse (fs) and high-intensity (>10²⁰ W.cm^-2), diverse laser technologies have facilitated the exploration and comprehension of a vast array of plasma physics phenomena. This lecture aims to provide an overarching understanding of the diverse physics domains influenced by laser-plasma interaction, ranging from nuclear fusion to high-field physics. Furthermore, it will present the technologies employed in conducting experiments at large-scale infrastructures within these distinct fields, using the P3 platform at ELI-Beamlines as an illustrative case.[1]

[1] https://www.sciencedirect.com/science/article/pii/S2468080X17300171 .

Optical coatings are used in every laser system for light beam control and manipulation. The power of current laser systems is constantly increasing, and coatings are exposed to higher and higher intensity radiation. Therefore, progress in materials engineering, theoretical modeling of multilayer structures, and thin film deposition conditions are in constant need. Most of the high-power laser systems are restricted by the limitations in optical coatings, especially the laser power they can withstand without permanent damage.

ELI Beamlines is a part of the world’s largest high-power laser infrastructure. We are in constant need of the highest quality optical components and especially coatings. Given the complexity of the laser systems in the whole ELI ERIC, most of the current progress in optical coatings has already been investigated and implemented. The variety of laser systems allows us to be part of the progress in ultrafast optics, metal mirrors, diffraction gratings, antireflection coatings, etc. Therefore, for the past several years the optical coatings laboratory in ELI ERIC, ELI Beamlines facility has been developing the measurement tools for determining the characteristics of provided optics. Additionally, we are currently building our capabilities for manufacturing and developing state-of-the-art optical coatings for high-power laser systems.

During the talk, the technologies and their current progress will be described for manufacturing high quality optical coatings for high-power laser applications. The main characteristics which are required for high quality optics will be discussed together with their measurement techniques and procedures. The focus will be dedicated to laser damage phenomena, ultrafast optics, and challenges for large area optics. Finally, the current situation and the plan for the future of optical coatings development in ELI Beamlines will be presented.