The main objective of the Research Program 2 is the development of high-energy class diode-pumped solid-state lasers. First operation of the multi-slab laser at HiLASE (“Bivoj”) at the end of 2016 demonstrated amplification of 10 ns pulses at 10 Hz pulse repetition rate to an energy of 105 J at 1029.5 nm, representing the world’s first kW average power, high-energy, nanosecond pulsed diode pumped solid state laser. We also work on associated laser technologies, which include high-power optical isolators, adaptive optics, and characterization of laser materials at cryogenic temperatures.
Efficient, high energy, pulsed laser systems operating at high pulse repetition rates (10 Hz and beyond) are required for a wide range of commercial and scientific applications, including advanced materials processing, laser shock treatment of mechanical components, and pumping of ultra-high intensity fs petawatt-class lasers to generate high-brightness secondary radiation (x-ray, gamma-ray) and particle (electron, proton, ion, muon) sources. These have potential applications for novel medical therapies, and in high-resolution radiography and advanced imaging for industrial and security sectors.
Successful operation of Bivoj 10 J laser
The Bivoj team has successfully provided more than 2.5 × 10^7 pump pulses resulting in reliable, stable and high-energy laser operation (2-6 J) in the period of August 2017-July 2018. These laser shots were used for internal tests and for several experimental campaigns, including LSP, LIDT and laser-generated ions. A key laser parameter for the successful operation of Bivoj is the wavefront quality. Jan Pilar received a Student Poster Award for his work on ‘Adaptive Optics development at HiLASE’ at the 7th Conference of the International Committee on Ultrafast Intensity Lasers (ICUIL), Montebello, Canada, 11-16 September 2016.
Ceramic broadband materials for HAPP Lasers at HiLASE
Development of high average and peak power (HAPP) lasers requires laser materials with broad emission bands along with good thermo-mechanical and thermo-optical properties. Yb doped YAG shows excellent properties at cryogenic temperature which make them attractive material for such lasers. Nevertheless, at cryogenic temperature Yb:YAG exhibit very narrow bandwidth which limits the pulse width of Gaussian transform-limited pulses to pico-second. To address this limitation, we have introduced some disorder in the regular lattice to achieve inhomogeneous broadening in the emission spectra.
High energy second harmonic generation with 10 J Bivoj
The Bivoj team, led by Dr. Martin Divoky, and Dr. Jonathan Phillips from STFC, have successfully demonstrated high energy second harmonic generation (SHG) at 515 nm with a nonlinear LBO crystal at Bivoj laser system. The SHG experiment was performed utilizing the nanosecond Bivoj laser system at 1030 nm with an output energy of 5.9 J at 10 Hz. The aperture and the length of the LBO crystal were 25 mm and 13 mm, respectively. Figure below shows the long-term SHG output energy (green line) and the total fundamental energy (thick red line). Over an extended period of 110 minutes, the conversion efficiency remained stable with a SHG energy stability of 0.8% rms.
Antonio Lucianetti, RP2 leader: Putting curiosity to the use of society
Antonio Lucianetti received his Ph.D. in physics from University of Bern, Switzerland, in 1999. His research interests include high-energy cryogenic short pulse lasers, microchip lasers, high-energy optical isolators, laser-driven particle and radiation sources, and laser-based interferometric gravitational wave detectors. In 2017 he was awarded habilitation by the Italian Ministry of Education, University, and Research for full professor in the scientific sector ‘Experimental Matter Physics’. In the same year, he became a visiting Professor, National Institutes of National Sciences, National Institute for Fusion Sciences, Toki, Japan. He has authored/coauthored more than 135 journal articles and conference papers, with more than 4000 citations.