Delay line coherent pulse stacking of a symmetric mode-locked pulse train

Summary form only given. We show coherent pulse stacking of a symmetric mode-locked 47 MHz pulse train at 1558 nm using phase pre-shaping and delay lines. We also combine pulse stacking with spatial coherent beam combining and show how the concept can be scaled to an arbitrary number of pulses. This allows to scale the pulse energy of fiber amplifiers. There are several related methods, including divided pulse amplification (DPA) [1, 2] stack and dump- and low finesse cavities [3, 4, 5]. Unlike DPA, there are no dividers necessary in our approach and the amplified pulse train is symmetric. At the same time we avoid the use of potentially complicated cavities or dumpers.