Ways of achieving this include stimulated emission, triplet-state shelving and cis–trans isomerization, and more generally reversible saturable optical fluorescence transitions (RESOLFT).

The second innovation regards the centrepiece of the pulsed laser: a special mirror made of semiconductor material, which was invented by Keller 30 years ago , known as SESAM (Semiconductor Saturable ...

which was invented by Keller already thirty years ago and goes by the memorable abbreviation SESAM (Semiconductor Saturable Absorber Mirror). Unlike normal mirrors, the reflectivity of a SESAM ...