Control of the formation and amplification of pulse bursts in regenerative amplifiers

This paper presents control strategies to generate bursts of high-intensity laser pulses with arbitrary envelope from regenerative amplifiers by suitably adjusting the energy of the injected seed pulses. To this end, existing and experimentally validated models are generalized to obtain a dynamical model of the pulse formation and amplification. The resulting model is applicable to standard regenerative amplifiers as well as amplifiers with a detuned cavity specifically designed for the generation of pulse bursts. Utilizing this mathematical model, an optimization-based algorithm to obtain desired pulse bursts in steady state is presented. Since the quality of these feedforward solutions is limited due to parameter variations and model imprecisions, an adaptation scheme using iterative learning control methods is employed to track the desired burst envelope. Finally, the developed methods are combined with feedback strategies to allow for an operation in unstable regimes and the closed-loop behaviour is illustrated by simulation scenarios.