Fundamental and harmonic mode-locking with pulse repetition rate between 200 MHz and 6.8 GHz in a quantum-dot external-cavity laser

Semiconductor lasers with broad tunability of the pulse repetition rate in the range of MHz to GHz are very useful for non-linear imaging techniques, especially in the bio-medical field. In our previous work, we demonstrated a quantum-dot external-cavity passively mode-locked lasers (QD-ECMLL) incorporating a QD semiconductor saturable absorber mirror (SESAM) [1], generating pulses at repetition rates ranging from 1.5 GHz to 350 MHz. In a more recent investigation [2], a QD-ECMLL is demonstrated with pulse repetition rate as low as 310 MHz and corresponding harmonics up to 4 GHz (based on a fundamental frequency of ~1 GHz). We have demonstrated very recently the generation of high-peak-power picosecond pulses with repetition frequency from 2.4 GHz to 1.14GHz [3] using an external cavity output coupler of 96% transmissivity. © 2011 IEEE.