Abstract

Mode-locked laser diodes present important applications in the field of optical communications and are an interesting alternative to more conventional (sub)picosecond lasers for time-resolved spectroscopy and optical testing of various materials. During last years, many papers have been addressed to the experimental demonstration of laser diode mode-locking using different optical schemes and different types of diodes ^[1-4]. However, the mechanisms at the origin of coherent subpicosecond mode-locked pulses in laser diodes still remain unknown. In view of a better understanding of this phenomena, we propose a non-invasive method for probing the gain medium during the mode-locking process. Results are presented for a passively mode-locked AlGaAs laser emitting pulses as short as ~450 fs.

© 1992 The Author(s)