FEMTOSECOND HYBRID MODE-LOCKED SEMICONDUCTOR-LASER AND AMPLIFIER DYNAMICS

We describe the generation of femtosecond high power optical pulses us ing hybrid passive-active mode-locking techniques. Angle stripe geomet ry GaAs/AlGaAs semiconductor laser amplifiers are employed in an exter nal cavity including prisms and a stagger-tuned quantum-well saturable absorber. An identical amplifier also serves as an optical power ampl ifier in a stretched pulse amplification and recompression sequence. A fter amplification and pulse compression this laser system produces 20 0 fs, 160 W peak power pulses. We discuss and extend our theory, and s upporting phenomenological models, of picosecond and subpicosecond opt ical pulse amplification in semiconductor laser amplifiers which has b een successful in calculating measured spectra and time-resolved dynam ics in our amplifiers. We have refined the theory to include a phenome nological model of spectral hole-burning for finite intraband thermali zation time. Our calculations are consistent with an intraband time of approximately 60 fs. This theory of large signal subpicosecond pulse amplification will be an essential tool for understanding the mode-loc king dynamics of semiconductor lasers and for analysis of high speed m ultiple wave-length optical signal processing and transmission devices and systems based on semiconductor laser amplifiers.