While the high-energy section of the L4 laser is based on well explored flash lamp technology pumping Nd:glass slabs, the unprecedented world’s most advanced performance is allowed thanks to a hybrid architecture, emploing the OPCPA frontend and Nd:glass powerr amplifiers.
In order to commission such a complex laser system, all the individual parts, including optics, timing system, controls, laser modules, etc. needed to be tested individually and then integrated into the L4 system. Several issues and challenges were successfully addressed during the development phase to assure a good beam quality at high energies and high repetition rates.
One exciting challenge was development of precise spectral control of the first part of the laser – the broadband OPCPA frontend. There, the pulse shape and spectrum profile are precisely tailored an advanced optimization algorithm, dramatically improving the performance of the main amplifier. The results of the optimization algorithm, developed by ELI scientists supporting the project, were recently published in Optics Letters [1] and the manuscript was selected as an “Editor’s pick” of the month.In July 2018, an independent panel evaluated the milestone D6: Integrated Operation of the Laser Chain and recommended Institute of Physics/ELI Beamlines to accept this Deliverable and go over to next milestones D7 and D8 (dismantling the system and packing for transport to ELI Beamlines; rebuilding of system at ELI Beamlines and integrating end-to-end operation of the laser chain to meet minimum performance requirements).
The panel congratulated the NE team in their achievement of building a unique world-leading laser system that can deliver over 1 kJ of energy at repetition rate almost an order of magnitude better than any other facility worldwide.
In September, the L4 laser is transferred in several batches to ELI Beamlines, where it will be built again and integrated into the facility’s laser beam transport, then brought up to full design specification – a high rep-rate, high energy kJ output with a 10 PW peak power after pulse compression, neither of which exists in the world today. ELI plans to make the L4 laser available by the end of 2019 to the international science user community.
The L4 laser will be a 10 PW system delivering 1.5 kJ femtosecond pulses once a minute. It will be the most energetic laser in ELI Beamlines and will also provide the highest peak power laser pulses.
[1] František Batysta, Roman Antipenkov, Teddy Borger, April Kissinger, Jonathan T. Green, Robertas Kananavičius, Gilles Chériaux, Dave Hidinger, Jonas Kolenda, Erhard Gaul, Bedřich Rus, and Todd Ditmire, “Spectral pulse shaping of a 5 Hz, multi-joule, broadband optical parametric chirped pulse amplification frontend for a 10 PW laser system,” Opt. Lett. 43(16), 3866-3869 (2018) – https://www.osapublishing.org/ol/abstract.cfm?uri=ol-43-16-3866
