Comparative study on the temporal contrast of femtosecond mode-locked laser oscillators.

We have investigated the temporal intensity contrast characteristics from a broad range of mode-locked short-pulse oscillators used for seeding high-power terawatt and petawatt-class laser systems. Saturable absorber (SESAM), Kerr lens (KLM), nonlinear polarization evolution (NPE) in optical fibers and synchronously pumped optical parametric oscillator (OPO) mode-locked sources have been measured using a third-order autocorrelator with up to 10¹⁰ dynamic range. We restricted the temporal characterization to features <30  ps about the laser pulse that reflect fundamental mode-locking processes. We find additional nonlinear terms and residual higher-order dispersion limits the performance of KLM and NPE sources up to the 10⁵ contrast level, while >10⁸ contrast was observed from the SESAM and OPO laser pulse trains.