Solid-state laser

A laser that amplifies light by stimulated emission in a solid gain medium, usually a crystal or glass doped with optically active ions.

Laser gain medium: The material in which stimulated emission amplifies light inside a laser. Doped crystals and glasses provide the ions whose transitions supply optical gain.
Nd:YAG laser: A solid-state laser using neodymium-doped yttrium aluminum garnet as its gain medium. It is a widely used example of a crystal laser with a four-level neodymium transition.
Q-switching: A method that stores energy in a laser medium and releases it as a short, intense pulse by rapidly changing cavity losses. It produces high-peak-power pulses from solid-state gain media.
Gas laser: A laser whose gain medium is a gas or gas mixture. Gas media differ from doped solids in composition, pumping, and thermal behavior.
Optical pumping: Excitation of atoms or ions by absorbing light to create a nonequilibrium population of energy states. Flashlamps or diodes excite the active ions in many solid-state lasers.
Ruby laser: A pulsed laser whose gain medium is chromium-doped sapphire. Its chromium ions illustrate how dopants create laser transitions in a crystal host.
Mode-locking: A technique that phase-locks longitudinal laser modes to generate a periodic train of ultrashort pulses. Solid-state lasers such as titanium-sapphire systems can generate femtosecond pulses this way.
Dye laser: A laser that uses fluorescent organic dye molecules dissolved in a liquid as its gain medium. Dye lasers offer broad tunability but rely on a liquid rather than a solid host.
Population inversion: A condition in which more particles occupy an upper energy state than a lower state connected by a transition. The laser medium must be inverted so stimulated emission exceeds absorption.
Titanium-sapphire laser: A tunable laser using titanium-doped sapphire, with broad gain across much of the visible and near-infrared spectrum. Its broad emission band enables wavelength tuning and ultrashort pulses.

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Chemical oxygen–iodine laserCompared with: It contrasts with the oxygen–iodine laser’s chemically generated gaseous gain medium.