Performance of the novel high repetition rate HF-PW laser system of ELI ALPS is presented in its first operation phase at 400 TW and 700 TW levels. Long-term operation was tested at 2.5 and 10 Hz repetition rates, where an exceptional 0.66% and 1.08% shot-to-shot energy stability was demonstrated, respectively. Thorough spatio-spectral and temporal measurements confirmed high quality output pulses with a Strehl ratio of >0.9 after compression at both repetition rates. Amplified pulses with an unprecedentedly high 240 W average power were reached for the first time from a PW-class amplifier chain by using novel pseudo-active mirror disk amplification-based pump lasers.

We experimentally demonstrate the post-compression of radially polarized 25 fs pulses at 800 nm central wavelength in a multiple thin plate arrangement for the first time, to the best of our knowledge. Sub-7 fs pulses with 90 µJ energy were obtained after dispersion compensation, corresponding to a compression factor of more than 3.5. Preservation of radial polarization state was confirmed by polarized intensity distribution measurements. Linear projections of the radially polarized pulses were also fully characterized in the temporal domain.

We report on the generation of high-power narrow-bandwidth terahertz (THz) pulses by cryogenic cooling of hand-made periodically poled lithium niobate (PPLN) wafer stacks. As a proof-of-concept, we cool stacks with up to 48 wafers down to 97 K and achieve few-percent bandwidths at a center frequency of 0.39 THz, with pulse energy up to 0.42 mJ and average power of 21 mW. Supported by modeling, we observe effective cooling of PPLN wafer stacks that not only reduces terahertz absorption but critically maintains the micrometer-scale inter-wafer gaps for optimal terahertz transmission. Our results unlock the potential for scaling these large-area sources to greater numbers of wafers to push both the energy and bandwidth beyond current capability, opening up possibilities in areas such as terahertz-driven particle acceleration, terahertz imaging, and control over material properties.

We present a 10 mJ-class laser system based on a hybrid, femtosecond optical parametric and negatively chirped Ti:Sa-based amplification architecture. Output pulses with 13 mJ energy, 14.4 fs transform limited duration, and high spatio-spectral quality are reached at 100 Hz repetition rate centered at 788 nm wavelength. By compressing 1 mJ energy, a pulse duration of 15.5 fs is measured in combination with an intensity contrast higher than 10 ¹² already 15 ps before the main pulse. The presented architecture can be a robust and reliable solution for seeding sub-17 fs high intensity lasers with ultrahigh contrast at up to 100 Hz repetition rate.

Background/Objectives: Laser has a prominent place in pharmaceutical industry, especially in the marking of solid dosage forms (SDFs). To combat falsified medicines, this study evaluates QR code marking on the surface of tablets as a supplement to serialization on packaging, using an ultrafast laser to achieve industrially relevant marking speeds while preserving the functional integrity of double film-coated ibuprofen tablets. Methods: Tablets were directly compressed and coated with a double film: the inner layer was a gastro-resistant coating (Acryl-EZE^® MP), while the outer one was a coloured, TiO₂-containing (TC) or TiO₂-free (TF) immediate-release coating (Opadry^®). QR codes were ablated on the tablet surface using various laser parameters (e.g., pulse energy and scanning speed), and the effects were physically, chemically, and microscopically examined to evaluate their properties after this processing. Results: No significant differences were observed between TC and TF coatings. In addition, the readability of QR code is strongly influenced by laser settings and coating types. Furthermore, the used laser has achieved the expected fast marking speed and high-precision coding, which may be economically feasible for pharmaceutical companies. According to the profilometry findings, the ablation depth could be compensated for with an appropriate coating thickness to enable the desired release properties. This was confirmed by the results of SEM, Raman analysis, and in vitro dissolution test. Conclusions: Ultrafast Ti:Sa laser-based QR code marking directly onto the dosage form offers increasing benefits in the healthcare field. However, it may undesirably affect the behavior of the dosage form. This requires careful consideration of formulation and laser processing conditions before application, especially in the case of delayed-release (DR) systems.