SESAM modelocking

The basic principle of ultrashort pulse generation is the introduction of a saturable loss mechanism into the laser cavity. High Q Laser Systems use SESAM modelocking to generate ultrashort pulses.
In SESAM modelocking a mirror with an intensity dependent absorption behavior is used in the resonator to obtain a self-amplitude modulation of the radiation. The reflectivity of the mirror is increased for higher intensities leading to an amplification of lower-loss coupled modes.