Abstract

During last years, active mode-locking of semiconductor lasers in an external cavity has been the subject of many studies.^[1,2,3] Strong feedback from the external reflector along with AR coating of the internal diode facet are generally considered as the most desirable conditions for obtaining short pulses with this configuration. In this paper, we propose and analyze a different situation where a gain-/Q-switched laser diode is coupled to a highly-attenuating, selective external cavity. The laser behaviour is shown to radically differ from that observed with strong feedback. Actually, we evidence a certain analogy with the case of a pulsed laser with small CW injection signal.^[4] Unlike previous experiments on semiconductor lasers with selective external cavity.^[5] very large phase modulation is obtained in single-mode emission leading to ultrashort (~1ps) tunable (~35nm) pulses after compression.

© 1992 IQEC