Conclusion
Passive saturable absorbers for short-pulse lasers

In this article, we show that several types of saturable absorber materials and structures can be used in laser cavities in an extremely simple way to induce Q-switching or mode-locking operation and obtain ultra-short laser pulses from nanoseconds to femtoseconds.

While the dominant technology for the production of nanosecond pulses in the Q-switching regime is still based on the use of crystals doped with transition ions from the iron group, the prevailing technology for the production of sub-picosecond pulses in the mode-locked regime, based on semiconductor mirrors of the SESAM type, may soon be superseded.

Once the manufacture and packaging of nanomaterials in thin film or nanoparticle form are better mastered, they will offer a relevant alternative to SESAM.

By being made from semi-metals or semiconductors,...