Synchronization of a 60 MHz-Er:fiber-laser and a 100 MHz-Ti:Sa-laser

Summary form only given. In contrast to the synchronization of two Ti:sapphire lasers with identical repetition rates and a spectral overlap presented previously (Shelton et al. 2001), we pulse-synchronize a 60 MHz Er fiber laser with a 100 MHz Ti:sapphire laser. The pulses of the fiber laser are of approximately 80 fsec duration with a spectral width of some 100 nm centered around 1560 nm, whereas the Ti:sapphire laser's pulses are significantly shorter (about 10 fsec) and its spectrum comprises approximately 200 nm centered around 780 nm. We employed a similar principle for pulse-synchronization as presented by Shelton, that is detection and phase-locking of high harmonics of the repetition rate. However, we additionally introduced tunable phase-offsets of arbitrary magnitude in the phase-lock-loop and thereby controlled the relative delay between pulses from the two lasers. (We chose lasers differing in repetition rate and spectral region of emission to show general applicability.) In our case the relative delay between pulses is controlled electronically, which abolishes the need for a variable delay-line in order to retard one pulse with respect to the other. This is advantageous, if long delays are desired, since the necessary geometric delays may alter the pump-probe-overlap. In a first test we measured the cross-correlation (sum frequency generation) of the Er fiber laser and the Ti:sapphire laser pulses in a LiIO/sub 3/ crystal, verifying pulse synchronization much better than the 80 fsec pulse length of the fiber laser.