Abstract

In the past three years, self-mode-locked ~10 fs-pulse^1,2 generation have been demonstrated in ion-laser pumped titanium- doped Al₂O₃ (Ti:sapphire) lasers. Since the self-mode-locking is induced by a field modulation by the optical nonlinearity, those lasers required high pumping powers. A low mode-lock threshold will be a major advantage to obtain compact and reliable femtosecond sources. The mode-lock threshold can be decreased in a high-Q cavity,³ but it is hard to obtain good stability and high efficiency. Recently, Zhou et al⁴ has shown that the duration of a circulating pulse is modified by dispersion of each intra-cavity component in a self-mode-locked Ti:sapphire laser. We considered a new approach to decrease the mode-lock threshold, taking account of the intracavity pulse-spreading.

© 1995 IEEE