They were initially used in a Resonant Pulse Modelocking (RPM) scheme as starting mechanisms for Ti:Sapphire lasers which employed KLM as a fast saturable absorber.
"For almost two decades since then, her group at ETH Zurich has continued to define and push the frontier in ultrafast solid-state lasers both with detailed theoretical models and with world-leading experimental results, demonstrating orders of magnitude improvement in key features such as pulse duration, energy, and repetition rate.
Today most ultrashort lasers are based on SESAM modelocking, with important industrial applications ranging from optical communication, precision measurements, microscopy, ophthalmology, and micromachining.
[quantify] For example, saturation fluence can be controlled by varying the reflectivity of the top reflector while modulation depth and recovery time can be tailored by changing the low temperature growing conditions for the absorber layers.
This freedom of design has further extended the application of SESAMs into modelocking of fiber lasers where a relatively high modulation depth is needed to ensure self-starting and operation stability.