Why are low-temperature MBE grown semiconductors important for an all-solid-state ultrafast laser technology?

We generate pulses from nanoseconds to 10 fs by varying the semiconductor saturable absorber and laser cavity design. In the long pulse regime with pulses as short as 180 ps, we rely on passive Q-switching. In the picosecond regime, we use the fast saturable absorber modelocking technique, and in the femtosecond regime, the semiconductor saturable absorber stabilizes soliton modelocking. In all cases, we benefit from the large design freedom of the antiresonant Fabry-Perot saturable absorber (A-FPSA) concept using low-temperature MBE growth to artificially adjust the physical parameters such as recovery times, saturation fluence, saturation intensity, insertion loss and modulation depth