Innovation Solutions for Scaling High Energy Ultrafast Lasers to Multi-Kilowatt Average Power for Compact Accelerators and Applications

Laser driven plasmas have the potential to reduce the size of particle accelerators by orders of magnitude with respect to conventional accelerators based on radiofrequency technology. This makes laser-plasma accelerators attractive for many applications, that in the short term include compact bright x-ray and gamma ray sources, and in the long term the future generations of particle colliders. Advances in compact laser-driven plasma accelerators depend on the availability of efficient femtosecond lasers capable of delivering multi-Joule pulses at kHz repetition rates. However, the laser parameters required for these applications significantly surpass the state-of-the-art of ultrashort pulse lasers.

Building on recent results, we plan to investigate the scaling of the laser pulse energy and average power of cryogenically cooled diode-pumped Yb:YAG pulse laser amplifiers. This demands the development of superior thermal management techniques with greatly increased heat removal capacity, and solutions to other key barriers. We plan to demonstrate cryo-cooling of Yb:YAG amplifiers in a multi-kW laser testbed, demonstrate energy scaling of uncompressed laser pulses, and investigate spectral broadening for pulse compression to sub-100 fs pulse duration. We will also investigate high damage threshold multilayer dielectric optical coatings at high average power, and will use the high average power laser testbed to validate modeling tools that will enable further scaling of high average power/high pulse energy solid state lasers with reduced risk. Students will be trained in advanced high power lasers for accelerators, and will be prepared to make significant contributions to the field.