500 W average power, multicore fiber-based femtosecond CPA system

We present a rod-type, Ytterbium-doped, multicore fiber with 4x4 cores. This fiber is employed in a CPA setup for coherent beam combination of femtosecond pulses. High average powers of up to 507 W after combination and compression could be achieved at 10 MHz repetition rate. A high combination efficiency of 85% could be realized together with an excellent beam quality. Additionally, up to 600 μJ pulse energy was measured in a lower repetition rate configuration.