We report on frequency doubling of high-energy, high repetition rate ns pulses from a cryogenically gas cooled multi-slab ytterbium-doped yttrium aluminum garnet laser system, Bivoj/DiPOLE, using a type-I phase matched lithium triborate crystal. We achieved conversion to 515 nm with energy of 95 J at repetition rate of 10 Hz and conversion efficiency of 79%. High conversion efficiency was achieved due to successful depolarization compensation of the fundamental input beam.

Development of high energy laser sources with nanosecond pulses at several hertz values for repetition rate has been very attractive in recent years due to their great potential for practical applications. With the recent advancement in fabricating large size laser quality transparent ceramics, diode pumped solid-state laser generating pulse energy of 100 J at 10 Hz has been recently realized at HiLASE center using Yb:YAG ceramic with Cr:YAG cladding. This review discusses Yb based high energy lasers, specific laser geometries for efficient thermal management and the role of transparent ceramics in such diode pumped high-energy-class solid-state lasers around the world.

Faraday effect measurements of holmium oxide (Ho₂O₃) ceramics-based magneto-optical materials, highly potential material candidates for high-energy laser Faraday isolators, are presented in this paper. Temperature dependence of the Verdet constant of nondoped Ho₂O₃ ceramics was measured for temperatures 15–305 K at $1.064~\unicode[STIX]{x03BC}\text{m}$ wavelength. The Verdet constant dispersion for wavelengths 0.5–$1~\unicode[STIX]{x03BC}\text{m}$ and $1.064~\unicode[STIX]{x03BC}\text{m}$ was measured for both nondoped Ho₂O₃ ceramics and Ho₂O₃ ceramics doped with terbium Tb³⁺ (0.2 at. %) and cerium Ce³⁺ (0.1 at. %) ions. The results suggest that the relatively low level of doping of Ho₂O₃ with these ions has no significant boosting impact on the Faraday effect. Therefore, other compositions of Ho₂O₃ ceramics-based magneto-optical materials, as well as various doping concentrations, should be further examined.

We present the workflow of the design, realization and testing of deformable mirrors suitable for high power diode pumped solid-state lasers. It starts with the study of the aberration to be corrected, and then it continues with the design of the actuators position and characteristic. In this paper, we present and compare three deformable mirrors realized for multi-J level laser facilities. We show that with the same design concept it is possible to realize deformable mirrors for other types of lasers. As an example, we report the realization of a deformable mirror for femtosecond lasers and for a CW CO2 laser.Regional Development Fund, the European Social Fund and the state budget of the Czech Republic (project HiLASE: CZ.1.05/2.1.00/01.0027, project DPSSLasers: CZ.1.07/2.3.00/20.0143). This research was partially supported by the grant RVO 68407700.

Further advancement of high-energy pulsed lasers requires a parallel development of appropriate optical components. Several different optical components, such as mirrors and antireflection-coated windows, which are essential for the design of HiLASE high average power lasers were tested. The following paper summarizes results on the measurements of laser-induced damage threshold of such components, and clearly shows their capabilities and limitations for such a demanding application.This work is co-financed by the European Regional Development Fund, the European Social Fund and the state budget of the Czech Republic (project HiLASE: CZ.1.05/2.1.00/01.0027, project DPSSLasers: CZ.1.07/2.3.00/20.0143, project Postdok: CZ.1.07/2.3.00/30.0057). This research was partially supported by the grant RVO 68407700.

A preliminary investigation on short-wavelength ablation mechanisms of poly(methyl methacrylate) (PMMA) and poly (1,4-phenylene ether ether-sulfone) (PPEES) by extreme ultraviolet (EUV) radiation at 13.5 nm using a table-top laserproduced plasma from a gas-puff target at LLG (Gottingen) and at 46.9 nm by a 10 Hz desktop capillary discharge laser operated at the Institute of Physics (Prague) is presented. Ablation of polymer materials is initiated by photoinduced polymer chain scissions. The ablation occurs due to the formation of volatile products by the EUV radiolysis removed as an ablation plume from the irradiated material into the vacuum. In general, cross-linking of polymer molecules can compete with the chain decomposition. Both processes may influence the efficiency and quality of micro(nano)structuring in polymer materials. Wavelength is a critical parameter to be taken into account when an EUV ablation process occurs, because different wavelengths result in different energy densities in the near-surface region of the polymer exposed to nanosecond pulses of intense EUV radiation.

We present the results of performance modeling of a diode-pumped solid-state HiLASE laser designed for use in inertial fusion energy power plants. The main amplifier concept is based on a He-gas-cooled multi-slab architecture similar to that employed in Mercury laser system. Our modeling quantifies the reduction of thermally induced phase aberrations and average depolarization in Yb3C:YAG slabs by a combination of helium cryogenic cooling and properly designed (doping/width) cladding materials.