Basic consideration on coherent combining of ultrafast CPA amplifiers

Coherent combining of ultrashort pulses from spatially separated amplifiers is a novel approach to scale the average power and peak power of laser systems. For continuous-wave and Q-switched laser systems this is a widely known concept. Recently, this approach was adapted to femtosecond CPA systems in a low power proof of principle experiment [1]. Compared to the CW and Q-switched case, additional aspects have to be considered when combining femtosecond pulses, such as dispersion management and the impact of nonlinear effects. This is especially true for fiber based systems.