77 GHz repetition rate from a soliton mode-locked Nd:YVO/sub 4/ laser

Summary form only given. Recently, we have demonstrated passively modelocked miniature Nd:YVO/sub 4/ lasers which generate pulse trains at extremely high repetition rates of up to 59 GHz. At these repetition rates, we were approaching the limit which is set by the pulse duration of typically 5-6 ps: the pulse spacing is so small that consecutive pulses begin to overlap, thus making a further increase in repetition rate not possible. Now we have found a way to push the mentioned limit significantly further. Even more than 100 GHz repetition rate now seems possible: we apply soliton mode locking, exploiting negative dispersion which results from a GTI-like effect at a small air gap between the laser crystal and the SESAM/sup ./ With this technique, we achieve a significantly reduced pulse duration of 2.7 ps, so that the pulse overlap becomes very small. Also the tendency for Q-switching instabilities, which is a severe challenge for passive mode locking at high repetition rates, is significantly reduced by soliton effects. As a first result obtained with this technique, we present a 77 GHz laser with 2.7 ps pulse duration and 65 mW output power. To our knowledge, this is the highest repetition rate ever obtained from a rare-earth-doped laser, and the pulse duration is the shortest demonstrated with a Nd:YVO/sub 4/ laser. We believe that this technique will in the near future allow us to obtain repetition rates above 100 GHz.