A solid-state laser is a laser that uses a gain medium that is a solid, rather than a liquid such as in dye lasers or a gas as in gas lasers. Semiconductor-based lasers are also in the solid state, but are generally considered as a separate class from solid-state lasers (see Semiconductor laser).
Generally, the active medium of a solid-state laser consists of a glass or crystalline host material to which is added a dopant such as neodymium, chromium, erbium, or other ions. Many of the common dopants are rare earth elements, because the excited states of such ions are not strongly coupled with thermal vibrations of the crystalline lattice (phonons), and the lasing threshold can be reached at relatively low brightness of pump.
There are many hundreds of solid-state media in which laser action has been achieved, but relatively few types are in widespread use. Of these, probably the most common type is neodymium-doped YAG. Neodymium-doped glass (Nd:glass) and ytterbium-doped glasses and ceramics are used in solid-state lasers at extremely high power (terawatt scale), high energy (megajoules) multiple beam systems for inertial confinement fusion. Titanium-doped sapphire is also widely used for its broad tunability.
Solid state lasing media are typically optically pumped, using either a flashlamp or arc lamp, or by laser diodes. Diode-pumped solid-state lasers tend to be much more efficient, and have become much more common as the cost of high power semiconductor lasers has decreased.
Notes and references
- Fulghum, David A. "Lasers being developed for F-35 and AC-130." Aviation Week and Space Technology, (8 July 2002). Access date: 8 February 2006.
- Morris, Jefferson. "Keeping cool a big challenge for JSF laser, Lockheed Martin says." Aerospace Daily, 26 September 2002. Access date: 3 June 2007.
- Fulghum, David A. "Lasers, HPM weapons near operational status." Aviation Week and Space Technology, 22 July 2002. Access date: 8 February 2006.
- Koechner, Walter (1999). Solid-State Laser Engineering (5th ed. ed.). Springer. ISBN 3-540-65064-4.