Multi-Terawatt, 50fs Laser for Laser Accelerator Applications--Positive Light, Inc., 101 Cooper Court, Los Gatos, CA 95032-7604; 408-399-7744
Mr. Rimas Viselga, Principal Investigator
Mr. Jeremy Weston, Business Official
DOE Grant No. DE-FG03-99ER82860
Amount: $749,718

The Department of Energy has a need for terawatt-class laser systems for advanced laser-driven particle acceleration applications. Specifically, compact multi-terawatt systems are sought that are capable of providing at least 1 joule (J) in 50 femtosecond (fs) single wavelength pulses or, alternately, 60 J, 4 picosecond (ps) pulses in dual wavelength operation. This project will develop a compact terawatt chirped pulse amplifier laser system using titanium-doped sapphire (Ti:sapphire) as the gain medium to achieve short pulse widths. By combining a 10-femtosecond seed laser and a cylindrical mirror pulse expander with two multi-pass amplifier stages, this system will generate multi-terawatt, 50 femtosecond pulses. Peak powers up to 5 terawatts at 10 Hertz are feasible. If arrangements can be made to pump the final amplifier with a neodymium-doped glass laser developed earlier, then the goal of 50-femtosecond pulses that exceed 20 terawatts will be achieved. In Phase I, the ~110 femtosecond, ~400 microjoule pulses from an available commercial ultrafast regenerative amplifier system were amplified to ~155 millijoules in a 16-mm diameter, four-pass Titanium sapphire amplifier. Based on these results, calculations show that further amplification would offer the potential for pulse energies up to 0.5 Joules at 10-Hertz. Phase II will develop and characterize a compact, chirped pulse amplifier system based on titanium-sapphire, tailored to laser-accelerator applications. This system will deliver peak powers greater than 5 terawatts at 10 Hertz. When combined with an existing neodymium-glass laser, peak powers greater than 20 terawatts should be possible. A secondary goal of Phase II will be to demonstrate the simultaneous amplification of two pulses at two closely spaced frequencies.

Commercial Applications and Other Benefits as described by the awardee: The availability of compact, relatively affordable laser-driven particle accelerators should lead to numerous potential commercial applications involving synchrotron optical sources, free electron lasers and sub-atomic particles. These applications include biomedical imaging, therapy, metallurgy and protein crystallography (accelerators) and surface science.