Scaling of petawatt-class lasers to multi-kHZ repetition rates

Petawatt laser applications, such as laser plasma acceleration, EUV generation, neutron generation, and materials processing are average-power limited. However, the highest average-power petawatt-class laser to date has an average power of less than 1 kW. Scaling Petawatt-class lasers beyond 10 kW of average power requires a paradigm shift in laser design. To date, average power scaling has been accomplished by increasing the repetition rate of single-shot lasers, in which each shot represents a complete pump/extraction cycle. We propose an alternative scheme, multipulse extraction, in which the gain medium is pumped continuously and the upper state population is extracted over many pulses. This method has two primary benefits: First, because efficient extraction is not necessary in a single pulse, the extraction fluence (and hence the B-integral) can be much lower than in a single pulse design. Second, there isn’t a need to pump within a single inverse lifetime, and therefore less expensive, less complex, and more efficient CW pump sources can be used. Multipulse extraction requires that the gain material have an inverse lifetime significantly less than the desired repetition rate. The design and optimization two multipulse extraction amplifiers, a 10 kHz-100 fs-30J amplifier and a 200 Hz-240 fs-240 J amplifier, will be presented. These point designs have applications in laser plasma acceleration and neutron generation, respectively