Abstract

Recently, it has been demonstrated in a Ti:Al₂O₃ [1] that the nonlinear external coupled-cavity acted as a passive mode-locker to generate a stable train of pulses without synchronous pumping or active mode-locking. To date, all the demonstrations of coupled-cavity mode-locking using a nonlinear external cavity are in lasers with gain media which have extremely broad bandwidths, such as color center crystals [2] or Ti:Al₂O₃ [1]. To our knowledge, cw passive mode locking in a narrow-bandwidth neodymium laser, such as Nd:YAG or Nd:YLF, has never been demonstrated. In this paper, we report cw passive mode locking operation of the Nd:YLF laser with a nonlinear external coupled-cavity using an optical fiber as the nonlinear medium. We have obtained nearly transform-limited pulses as short, as 3.67 ps at usable average output power up to 7 W.

© 1990 Optical Society of America