All-optical synchronization and mode locking of solid-state lasers with nonlinear semiconductor Fabry-Perot mirrors

The dynamics of laser oscillators can be directly accessed by modulating the intracavity losses. The authors present a new approach of optically driven loss modulation by means of a nonlinear semiconductor mirror based on a Fabry-Pe´rot structure [Fabry-Pe´rot modulator (FPM)]. The modulation depth of this device can be several percent and the response time is dominated by the recombination time of the generated free carriers inside the semiconductor, which can be reduced by ion implantation. This paper reviews the design of the FPMs and their optical characterization via spectrally resolved two-color pump-probe spectroscopy. Applications of the FPM are the synchronization of the pulse trains of independent mode-locked laser oscillators. The authors demonstrate the synchronization of a ps-Nd:YVO₄ laser to a fs-Ti:sapphire laser in a master-slave configuration and show experiments on the carrier-envelope phase relationship between the two synchronized pulse trains. Finally, they show that it is possible to actively mode lock a solid-state laser by an optically driven FPM. The resulting pulsewidths of the actively mode-locked Nd:YVO₄ laser are as short as 6 ps, which is comparable to passively generated pulses.