Active pump-seed-pulse synchronization for OPCPA with sub-2-fs residual timing jitter

Short-pulse-pumped optical parametric chirped pulse amplification (OPCPA) requires a precise temporal overlap of the interacting pulses in the nonlinear crystal to achieve stable performance. We present active synchronization of the ps-pump pulses and the broadband seed pulses used in an OPCPA system with a residual timing jitter below 2 fs. This unprecedented stability was achieved utilizing optical parametric amplification to generate the error signal, requiring less than 4 pJ of seedand 10 μJ of pump-pulse-energy in the optical setup. The synchronization system shows excellent long-term performance and can be easily implemented in almost any OPCPA system.