Femtosecond mode-locked semiconductor disk lasers

Abstract

The generation of ultrashort pulses with passively mode-locked semiconductor disk lasers (SDLs) incorporating only an optically-pumped surfaceemitting semiconductor gain element and a semiconductor saturable absorber mirror (SESAM) is presented. The optimum parameters for nearly Fourier-limited femtosecond pulses in single- or multiple-pulse regimes are investigated. On the basis of the experience gained a harmonically mode-locked SDL emitting sub- 200 fs pulses at a very high repetition rate of 92 GHz and a fundamentally mode-locked SDL generating practically chirpfree pulses with durations close to 100 fs at a rate of 5 GHz are demonstrated in the 1-µm wavelength range. The latter set a record for shortest pulse durations achieved directly from any fundamentally or harmonically mode-locked semiconductor laser. Overall, the results are a further step of modelocked SDLs in becoming useful compact and low-cost ultrashortpulse sources.