Seise, E.E.SeiseKlenke, A.A.KlenkeLimpert, J.J.LimpertTünnermann, A.A.Tünnermann2022-03-042022-03-042010https://publica.fraunhofer.de/handle/publica/22368510.1364/OE.18.027827We report on a novel approach of performance scaling of ultra-fast lasers by means of coherent combination. Pulses from a single mode-locked laser are distributed to a number of spatially separated fiber amplifiers and coherently combined after amplification. Splitting and combination is achieved by polarization cubes, i.e. the approach bases on polarization combining. A Hänsch-Couillaud detector measures the polarization state at the output. The error signal (deviation from linear polarization) is used to stabilize the synchronization of different channels. In a proof-of-principle experiment the combination of two femtosecond fiber-based CPA systems is presented. A combining efficiency as high as 97% has been achieved. The technique offers a unique scaling potential and can be applied to all ultrafast amplification schemes independent of the architecture of the gain medium.en620621journal article