Sub-15-femtosecond active synchronization of two passively mode-locked Ti:sapphire oscillators

Summary form only given. The ability to synchronize a passively-modelocked laser to an external reference, or to a second laser, has many applications. Previous work synchronizing two mode-locked Ti:sapphire lasers has demonstrated timing jitters of at best a few hundred femtoseconds. Since it is now routine to generate pulses with duration <20 fs, improved techniques would make it possible to take full advantage of this time resolution for applications such as sum- and difference-frequency mixing, novel pulse generation and shaping techniques, and for novel laser/accelerator based light sources. This paper presents a new technique that allows us to robustly synchronize pulse trains from separate lasers with a timing jitter of <15 fs. We use two independent mode-locked Ti:sapphire lasers, running at 780 nm and 820 nm. Our synchronization scheme consists of three phase lock loops working at different timing resolutions.