Solid-state laser
A solid-state laser is a laser that uses a gain medium that is a solid, rather than a liquid as in dye lasers or a gas as in gas lasers.[1] Semiconductor-based lasers are also in the solid state, but are generally considered as a separate class from solid-state lasers, called laser diodes.
Mode locking[edit]
Mode locking of solid-state lasers and fiber lasers has wide applications as large-energy ultra-short pulses can be obtained.[1] There are two types of saturable absorbers that are widely used as mode lockers: SESAM,[8][9][10] and SWCNT. Graphene has also been used.[11][12][13] These materials use a nonlinear optical behavior called saturable absorption to make a laser create short pulses.