Abstract

Previously, we have introduced a spectral filtering technique and applied it to a passively modelocked Nd:glass laser using an antiresonant Fabry-Perot saturable absorber (A-FPSA) [1]. Pulses as short as 130 fs are achieved in a standard dispersion compensated delta - cavity design with a 4mm Nd:glass plate inserted at Brewster's angle. The Nd:glass laser system is interesting from the point of view of an all solid state laser technology because it can be diode pumped. To further investigate the modelocking dynamics in Nd:glass lasers, we performed the following experiments: First we demonstrated a regeneratively, actively mode-locked phosphate Nd:glass laser (LG760, Schott), resulting in stable pulses with 310 fs pulsewidth, secondly a passively modelocked phosphate Nd:glass (LG700) laser with 105 fs and thirdly a passively modelocked silicate Nd:glass (LG680) laser with 92 fs. The passive modelocking experiments used an A-FPSA to both start and sustain stable mode locking without self-Q-switching. The different Nd:glass hosts were chosen because the phosphate Nd:glass can be considered as a quasihomogeneous laser material whereas the silicate Nd:glass is strongly inhomogeneous. Despite the completely different cw-behaviour of the lasers when the homogeneous or the inhomogeneous gain material is used, the modelocking performance is comparable and leads to almost the same pulsewidth in contrast to previously obtained results based on additive pulse mode locking [2]. Calculations as well as the experimental results show that KLM does not contribute to the modelocking performance.

© 1994 Optical Society of America