Mode locking using a type II multiple-quantum-well structure as a fast saturable absorber

We demonstrate the application of a type II Al(x)Ga((1-x))As/AlAs multiple quantum well as a fast saturable absorber in a hybridly mode-locked dye laser. Type II multiple quantum wells are promising for this application because of the fast recovery of the saturated absorption with picosecond or even subpicosecond time constants. We obtain almost transform-limited pulses as short as 0.9 psec for a type II sample with a recovery time of 2.3 psec.