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Thin disk regenerative amplifiers have suitable characteristics to pump picosecond OPCPA. By optimizing the trigger pulse to the MZM, a dual-output laser operating at 100 W, 1 kHz repetition rate, compressed to the transform limit is reported.

We report on the progress in developing a high energy, 1 kHz OPCPA auxiliary laser (F-SYNC) which is intended to supplement the L1-Allegra beamline. The auxiliary pulses are synchronized to the main laser with femtosecond precision and arbitrary delay.

We report on the performance improvements of the L1 Allegra laser system. The pump laser upgrade with the thin-disk multipass amplifier allows for the energy ramp-up, while a newly developed synchronized auxiliary laser system provides the capability of the pump-probe experiments at arbitrary delays.

Stable picosecond supercontinuum generated in long crystals is an excellent means of seeding broadband, high-energy CPA systems. The generated output energy and spectrum can be almost three times as stable as the pump for a wide range of input pulse parameters. In this work, we show this is an intrinsic property for crystals longer than the filament and for a range of input energy values. We present a description of the stability mechanism in both the visible and infrared regions together with experimental data that support the theoretical explanation.

We report on the current state of readiness of the 1 kHz, 15 fs L1 ALLEGRA laser system for long term reliable operation driving user experiments based on HHG. The highly automated system, based on short pulse OPCPA, currently generates pulses with energy of 30 mJ at central wavelength of 820 nm.

We report on the status of the Allegra laser beamline currently being commissioned at the ELI-Beamlines facility. The beamline will be used to drive X-ray sources for research in material science, molecular physics, and biophysics, where a high repetition rate is essential. Designed for user operation, significant attention is given to stability, reliability, and automation of the system. A photo of the beamline is shown in Fig. 1(a).

We report on the status of the Allegra laser beamline, which is designed to provide ub-20 fs pulses with tens of mJ of energy with exceptionally high contrast at a 1 kHz repetition rate.

We discuss the performance of several stages of high energy, high average power SHG and OPCPA with picosecond pulses in vacuum as part of the ALLEGRA laser at ELI-Beamlines.

We measure parameters of a stable supercontinuum generated in long YAG crystal, driven by 3 ps pulses at 1030 nm and evaluate the impact of initial conditions on supercontinuum stability.

For most extreme light applications, a reliable and stable driver laser is crucial to successful experiments. As lasers grow in energy and peak power they become increasingly complex and more failure modes are introduced to the system as a whole. For this reason it is prudent to develop a laser with simplicity, repeatability, and durability in mind. With the wide commercial availability of high quality, inexpensive fiber components, much of the required pulse conditioning for seeding high energy laser systems can take place entirely in fiber. This allows for much of the laser front end to be compact, alignment-free, and computer controlled with potentially dramatic savings in cost and space on the optical table. Here we explore some of the current trends in fiberbased front ends for high peak power laser systems. The requirements for any given high peak power laser are always quite different and fiber front ends are enormously customizable, so here we present two basic versions of fiber front ends which are used at the ELI-Beamlines facility which resemble other common fiber front end architectures.

Overview of progress in construction and testing of the laser systems of ELI-Beamlines, accomplished since 2015, is presented. Good progress has been achieved in construction of all four lasers based largely on the technology of diode-pumped solid state lasers (DPSSL). The first part of the L1 laser, designed to provide 200 mJ

We report on the status of the high repetition rate, high energy, L1 laser beamline at the ELI-Beamlines facility. The beamline is based on picosecond optical parametric chirped pulse amplification (OPCPA) of pulses from a mode-locked Ti:Sapphire oscillator and has a target energy/repetition rate of 100 mJ/1 kHz with < 15fs pulse duration. The OPCPA pump lasers use thin disk technology to achieve the high energy and average power required to pump such a high energy, high repetition rate broadband amplifier. Here we report on the progress in beamline development and discuss the technical challenges involved in producing such a system and their solutions. A major focus of the laser development is reliable, robust operation and long term stability; mechanical, optical, and control system architecture design considerations to achieve our goals of long term stability are discussed.

We present a stable supercontinuum (SC) generated in a bulk YAG crystal, pumped by 3 ps chirped pulses at 1030 nm. The SC is generated in a loose focus geometry in a 13 cm long YAG crystal, allowing for stable and robust single-filament generation. The SC energy stability exceeds that of the pump laser by almost a factor of 3. Additionally, we show that the SC spectrum has long-term stability and that the SC is coherent and compressible by compressing the portions of SC spectra close to the corresponding Fourier limit. This makes the picosecond-pulse-driven SC a suitable stable seed for OPCPA amplifiers.

We report on the design and performance of a fiber-based, multi-channel laser amplifier seed pulse distribution system. The device is designed to condition and distribute low energy laser pulses from a mode-locked oscillator to multiple, highly synchronized, high energy amplifiers integrated into a laser beamline. Critical functions such as temporal pulse stretching well beyond 100 ps/nm, pulse picking, and fine control over the pulse delay up to 300 ps are all performed in fiber eliminating the need for bulky and expensive grating stretchers, Pockels cells, and delay lines. These functions are characterized and the system as a whole is demonstrated by seeding two high energy amplifiers in the laser beamline. The design of this system allows for complete computer control of all functions, including tuning of dispersion, and is entirely hands-free. The performance of this device and its subsystems will be relevant to those developing lasers where reliability, size, and cost are key concerns in addition to performance; this includes those developing large-scale laser systems similar to ours and also those developing table-top experiments and commercial systems.

We present a stable supercontinuum generation in a YAG crystal, driven by 3 ps pulses at 1030 nm. The supercontinuum is demonstrated to be coherent and compressible by Dazzler and prism compressor to below 15 fs.

Laser sources generating radiation in the spectral range from 1.5 to 1.7 μm are very attractive for many applications such as satellite communication, range finding, spectroscopy, and atmospheric sensing. The goal of our research was an investigation of continuous-wave generation and wavelength tuning possibility of diode pumped eye-safe Er:YAG laser emitting radiation around 1645 nm. We used two 0.5 at. % doped Er:YAG active media with lengths of 10 mm and 25 mm (diameter 5 mm). As a pumping source, a fibre-coupled 1452 nm laser-diode was utilized, which giving possibility of the in-band pumping with a small quantum defect and low thermal stress of the active bulk laser material. The 150 mm long resonator was formed by a pump mirror (HT @ 1450 nm, HR @ 1610 - 1660 nm) and output coupler with 96 % reflectivity at 1610 - 1660 nm. For continuous-wave generation, the maximal output powers were 0.7 W and 1 W for 10 mm and 25 mm long laser crystals, respectively. The corresponding slope efficiencies with respect to absorbed pump power for these Er:YAG lasers were 26.5 % and 37.8 %, respectively. The beam spatial structure was close to the fundamental Gaussian mode. A wavelength tunability was realized by a birefringent plate and four local spectral maxima at 1616, 1633, 1645, and 1657 nm were reached. The output characteristics of the designed and realized resonantly diode-pumped eye-safe Er:YAG laser show that this compact system has a potential for usage mainly in spectroscopic fields.

The ELI Beamlines facility will house repetition rate high-power lasers with pulse durations down to 15 fs and over petawatt peak powers. Our research group participates in the construction of a cryogenically cooled Yb:YAG multi-slab amplifier; part of the L2 beamline. The system shall provide square, super-Gaussian beam with nearly 2 ns pulses with rectangular temporal profile and energy of up to 10 J at 10 Hz. The laser will provide pump beams for broadband OPCPA stages. The diagnostic system of the pump laser is critical for the correct performance analysis, stabilization feedback and mostly for the machine interlock system as damages of the expensive optical components can develop very fast with the 10 Hz repetition rate. The diagnostic system provides key laser parameters and characteristics in temporal, spectral and spatial domain. The paper describes testing of the setup for measurements of the final 10 J output. Its design is based on a combination of optical wedges and diffractive sampler to facilitate multiple diagnostics on a relatively small footprint. The laser diagnostics package covers measurements in spatial domain such as near-field, far-field, or wavefront analysis, further optical spectrum, pulse energy and temporal shape. In order to detect possible damage dark-field analysis was implemented as well. The final setup was modeled in optical design software (Radiant Zemax) to understand its behavior and later tested together with real-time LabVIEW code developed by our group as being part of the machine interlock system. The first results of the tests as well as detailed description of the diagnostics package design are presented.

Er:YAG crystal was investigated as gain medium in diode (1452 nm) pumped tunable laser. The tunability was reached in eye-safe region 1613-1656 nm by birefringent filter.

Er:YAG crystal was investigated as the gain medium in a diode (1452 nm) pumped tunable laser. The tunability was reached in an eye-safe region by an intracavity birefringent filter. The four tuning bands were obtained peaking at wavelengths 1616, 1632, 1645, and 1656 nm. The broadest continuous tunability was 6 nm wide peaking at 1616 nm. The laser was operating in a pulsed regime (10 ms pulse length, 10 Hz repetition rate). The maximum mean output power was 26.5 mW at 1645 nm. The constructed system demonstrated the tunability of a resonantly diode-pumped Er:YAG laser which could be useful in the development of compact diode-pumped lasers for spectroscopic applications.