The Secret Recipe for Passive CEP Stabilization

Carrier-envelope phase (CEP) stabilization is one of the key technologies for precision frequency metrology, for generating isolated attosecond pulses, and other high-field experiments. Traditionally, active feedback stabilization schemes were used. Second generation schemes resorted to a feed-forward approach, which typically outperform active stabilization. In the recent years, passive CEP stabilization [1] have also found widespread application. These schemes come in two variants, either coherently deriving seed pulses for pump and signal of an optical parametric amplifier (OPA) from a supercontinuum or using difference-frequency generation (DFG) from such a supercontinuum. While the simplicity of the passive approach is intriguing such schemes have only found little successful application, and resulting phase jitters were often found prohibitive for the above-mentioned applications. Based on measurements of our own and comparison with literature data, we have identified the rather surprising cause for poor performance of many – but not all [2]–[4] – passive CEP stabilization schemes.