State-of-the-art multi-Petawatt laser facilities coming online include the Zettawatt Equivalent Ultrashort pulse laser System (ZEUS), a user facility being commissioned at the University of Michigan. The 3-PW pulses will make ZEUS the highest power laser in the USA. This talk will describe the various experimental approaches that can be used to produce ultrashort particle beams and light-sources, as well as their application to study strong-field plasma physics and beyond. One area of interest is to create extremely strong magnetic fields within the hot plasma in the laboratory, so we can study the microphysics likely to be occurring around the most energetic objects in the universe.

On December 5th, 2022, the National Ignition Facility in Livermore, California, USA performed the first experiment demonstrating controlled fusion ignition in the laboratory. With a 2.05MJ UV laser drive energy delivered to the target, a neutron yield of 3.15MJ was released by the fusion reactions in the capsule, providing a net target gain of ~1.5×. The results of this experiment will be discussed, along with the decades-long developments in optical materials, laser architectures, target fabrication, and target diagnostics enabling this recent accomplishment. We will discuss the next steps for NIF and provide an outlook on future applications and technologies, including the reinvigorated pursuit of Inertial Fusion Energy.

Ultrahigh intensity laser – plasma physics is normally driven by lasers with few-10 fs or longer pulse duration. Certain applications involving the generation of isolated attosecond electron and x-ray pulses, however, require much shorter pulses that is not available from lasers. We report on the optical parametric synthesis of quasi-single cycle waveforms which can reach ultra-relativistic intensities up to 10^21 W/cm^2. A pulse duration below 4.5 fs is achieved by amplifying the spectrum between 580 – 1020 nm in two separate spectral regions in two consecutive optical parametric chirped pulse amplifiers. One stage pumped by 355 nm is optimized below 700 nm, while another pumped by 532 nm is optimized above 700 nm. This combination of amplifiers is called optical parametric synthesizer (OPS), which serially synthesizes the spectrum (full spectrum propagates through all amplifiers). Three such OPS double stages provide 440-500 mJ energy in the short light pulse corresponding to 100 TW peak power. Typical applications will be shortly introduced, such as electron acceleration from relativistic laser-plasmas and nonlinear attosecond x-ray interaction.

The OPCPA-based high energy 1 kHz laser system, operating at 820 nm provides exceptionally good contrast 15 fs pulses for a variety of user experiments at ELI Beamlines. The system is gradually upgraded to meet the demand of high energy high average power ultrashort pulse sources for the research in fields of HHG, X-ray generation and wake-field electron acceleration. The current parameters of the system are presented together a glimpse on recently performed state-of-the-art experiments.

More and more ultrafast few-cycle laser systems for strong field physics are operating at ultrahigh repetition rates reaching 50 kHz and more, where the extraction of the carrier-envelope phase (CEP) for each single pulse at higher repetition rates remains a challenge. We report here on a technique allowing the measurement of the CEP up to tens of MHz and it is demonstrated here at 100 kHz. Real time single-shot measurement/tagging of CEP at full (100 kHz) repetition rate is achieved by combining dispersive Fourier transform (DFT, TOUCAN) with field-programmable gate array (FPGA) technology for on-the-fly phase extraction from an 2f-to-f signal mapped to time domain.

KALDERA is DESY’s new flagship laser to drive a next-generation of laser-plasma accelerators, operating at kHz rep-rates and thus enabling fast active stabilization and feedback techniques to enhance the LPA performance. With this increase in average power, thermal management - especially in the final pulse compressor - becomes increasingly challenging. One potential solution is the use of multilayer dielectric (MLD) gratings, which absorb much less laser power and can thus reduce grating-deformation-induced pulse degradation significantly. We present a prototype MLD compressor, operated in an out-of-plane geometry, and a matched pulse stretcher based on transmission gratings, which act as a demonstrator for the KALDERA CPA system. We will show the design process of the system and present spectral and temporal characterization measurements performed at the system, including spectral efficiency, pulse shape, contrast, and polarimetry analysis. These measurements show that such a system can provide high-quality pulses at sub-30fs durations.

The L4n is a nanosecond-kilojoule laser beamline that delivers temporally shapeable nanosecond pulses at a maximum energy of 1.2 kJ. It was recently commissioned at ELI Beamlines and offers unique opportunities for high-pressure, high-energy-density physics, and laser-plasma interaction experiments, particularly due to its high repetition rate of up to 1 shot per minute. Compared to other kJ-class laser systems worldwide, which offer much lower shot rates, the L4n driven experiments will enable significant improvements in collecting data statistics. The results gathered during the first L4n commissioning campaigns, demonstrate the laser capability to deliver hundreds of joules every three minutes with excellent repeatability and clearly show its potential to make significant contributions to the field of high-energy density physics in the coming decades.

We report on the progress on developing a high energy, 1030 nm, 1 kHz, picosecond thin-disk multipass amplifier. Combining thin-disk technology with an imaging setup allows for reliable operation with good beam quality. We address the key challenges of beam-distortion by the disk and gain clamping due to parasitic lasing and how to overcome these.

The efficiency of optical parametric amplification (OPA) is fundamentally limited by its cyclic evolution behavior, which creates inefficient, asynchronous spatiotemporal conversion due to the local dependence of the conversion cycle on the field intensity. For Gaussian beam and pulse shapes, the pump photon depletion efficiency is typically only 10-30%, with ~1-20% of the pump energy going to the signal, limiting research involving high power ultrafast lasers. Using a new approach of hybridized nonlinear parametric processes in an ordinary OPA crystal using birefringent phase matching, we have achieved a mid-infrared parametric amplifier with 44% pump-to-signal conversion efficiency and high single-stage gain of 48 dB, while using a Gaussian-like pump spatiotemporal intensity profile. Our method uses simultaneously phase matched OPA and second harmonic generation phase matched at the idler wavelength to enhance the signal conversion efficiency via suppressed back-conversion while preserving the idler energy in a coherent copropagating field at twice its frequency. This “hybridized parametric amplification (HPA)” approach is a promising high-efficiency alternative to ordinary OPA. I will summarize an experimental demonstration of the amplifier [arXiv:2207.04147 [physics.optics]], and a theoretical explanation and an experimental verification of the wave evolution dynamics [Opt. Express 29, 30590 (2021); Phys. Rev. Lett. 129, 153901 (2022)].

Laser Induced Contamination (LIC) is one of the major issues in high energy high repetition rate laser systems. The growth of contamination during the operation of the laser influences the components spectral performance and can lead to the catastrophic damage. Several previous investigations indicate that LIC growth depends on the coatings material and even its deposition method. In our work, we investigate electron-beam deposited HR mirrors for the wavelength of 800 nm. Three different designs were tested in vacuum conditions under high repetition and high energy laser irradiation using femtosecond pulses. Two of the designs are based on quarter wavelength optical thickness (QWOT) layers: last layer of the first mirror is high refractive index film, hafnia in our case, and for the second mirrors the last layer was double QWOT of low refractive index film, silica in our case. For the last coating the E-field was modified by changing the last silica layer thickness. All samples were irradiated below the damage threshold level and LIC observed under confocal microscope. Analysis were obtained by comparing the influence of the last layer and E-field distribution within the multilayer coatings. Conclusions and recommendations for LIC reduction will be presented.

Results of the post-compression of SYLOS lasers to the single-cycle regime are presented with unprecedentedly high 1.1 TW to 2.7 TW input peak power. Spatial filtering of the input pulses and by utilizing a single thin fused silica plate as the nonlinear medium allowed us to reach well compressed 1.4- and 1.8-cycle pulses at 10 Hz and 1 kHz repetition rates starting from 12 fs and 7.5 fs durations, respectively. Spatio-spectral and temporal characterization of the compressed pulses confirmed their high quality. The >3 TW pulses will be used for ion acceleration and neutron generation experiments.

We conducted high energy nonlinear broadening experiments based on a gas-filled multipass cell seeded by a Yb-doped thin-disk regenerative amplifier (Dira 1000-5) capable of delivering 200 mJ pulses at a repetition rate of 5 kHz with durations below 500 fs. This setup recently demonstrated the possibility to compress 180 mJ pulses down to 42 fs without affecting the beam quality, while increasing the peak power by a factor of 12. In this work, we further characterize the output in terms of compressibility and beam quality.

Simulation strategy on efficiently combining 3+1D and 1+1D numerical simulations of high energy pulse post-compression in multiple thin plate compressor. While the main part of the optimization takes place in the 1D space, the final result describes the electric field of the pulse in the spatio-temporal space, and effected by third order nonlinearity, Raman-scattering, ionization and linear dispersion. The technique is compared to an experimental result where single cycle regime was reached, and the validation showed high accuracy. This method enables further optimization of post-compression for secondary sources, such as high harmonic generation and ion acceleration.

Within this work we demonstrate the efficient nonlinear temporal compression of mJ pulses emitted by an ultrafast thulium-doped fiber laser system. For spectral broadening, a krypton and helium filled Herriott-type multi-pass cell with broadband dielectric mirrors is employed. The input pulses with 1,78 mJ and 85 fs are spectrally broadened and subsequently compressed utilizing fused silica plates revealing a pulse duration below 29 fs while featuring an overall transmission of 91%. In addition to the preservation of the input beam quality, the system exhibits a shot-to-shot noise ratio of less than 1.2% as well as an excellent long-term power stability with fluctuations below 1% over a time span of 2 hours. The presented results demonstrate the advantageous properties of the multi-pass cell approach: High efficiency and high transversal beam quality at high average power, not only for conventional ultrafast ytterbium-based laser systems at 1 µm wavelength, but also in the mid-infrared regime. We believe that this system, delivering an average power above 162 W and sub-5-cycle pulse duration, provides a promising working point for following secondary source experiments like THz- or high harmonic generation.

In this work we report experimental compression of 9.4 mJ, 9.4 W, and 1.2 picosecond long pulses down to 7 mJ ,13 fs at 1 kHz in two cascaded stages with gas filled multi-pass cells (MPCs). The output from the first, argon filled MPC is compressed to <50 fs. The output pulses of the subsequent second MPC stage filled with Neon is then compressed to 13 fs using a chirped mirror compressor. The overall transmission, and compression ratio of both stages exceed 74 % and 92 times respectively.

Ultrahigh intensity lasers have been excellent tools in exploring the physics of superintense laser-matter interactions. The laser power has increased steadily to a multi-PW level by implementing the chirped pulse amplification (CPA) technique. Such a laser power can be further enhanced through a pulse shortening without additional the amplifiers. To enhance a peak power of a high energy femtosecond laser, the pulse shortening was investigated through a post-compression by installing a post-compression stage of a 100-TW CPA laser. The laser spectrum was broadened by the self-phase modulation (SPM) in thin fused silica plates and an induced dispersion was compensated by a set of chirped mirrors. The laser beam was post-compressed from 23 fs to 9.7 fs, corresponding to the peak-power enhancement by a factor of 2.1.

We will present in this paper the latest development made in the frame of High repetition rate PW laser. Increasing the repetition rate in high energy laser requires to master a lot of different parameters and especially the cooling and the reliability. We have worked in this direction in the frame of two projects: ELI ALPS in hungaria and HIBEF in Germany. We will show in the talk the developments that we have accomplished to reach at the same time a high energy and a high average power: specific pump laser (50J at 10Hz), High average power cryo cooling. We will then present the roadmap of Amplitude for higher repetition rate and in particular up to 100Hz which is required by the laser based accelerator

The 10 Hz repetition rate HF-2PW laser of ELI ALPS, which was designed to operate at 300 W average power, is being commissioned during the first ramping up phase. The system is currently running at the 10 J energy level and full energy compression was demonstrated for >2 hours of continuous operation with a pulse duration of 23 fs. Day-to-day operation represents an important milestone among next generation high peak and average power laser systems. During this period, fine tuning of pulse parameters, investigation of stability and reliability of the system is performed. Valuable experiences during operation are discussed in this paper.