Editing Laser (section)

=== Solid-state lasers ===

[[File:Starfield Optical Range - sodium laser.jpg|thumb|A 50 W [[frequency addition source of optical radiation|FASOR]], based on a Nd:YAG laser, used at the [[Starfire Optical Range]]]]

[[Solid-state laser]]s use a crystalline or glass rod that is "doped" with ions that provide the required energy states. For example, the first working laser was a [[ruby laser]], made from [[ruby]] ([[chromium]]-doped [[corundum]]). The [[population inversion]] is maintained in the dopant. These materials are pumped optically using a shorter wavelength than the lasing wavelength, often from a flash tube or another laser. The usage of the term "solid-state" in laser physics is narrower than in typical use. Semiconductor lasers (laser diodes) are typically ''not'' referred to as solid-state lasers.

[[Neodymium]] is a common dopant in various solid-state laser crystals, including [[yttrium orthovanadate]] ([[Neodymium-doped yttrium orthovanadate|Nd:YVO<sub>4</sub>]]), [[yttrium lithium fluoride]] ([[Nd:YLF]]) and [[yttrium aluminium garnet]] ([[Nd:YAG]]). All these lasers can produce high powers in the [[infrared]] spectrum at 1064&nbsp;nm. They are used for cutting, welding, and marking of metals and other materials, and also in [[spectroscopy]] and for pumping [[dye laser]]s. These lasers are also commonly [[second-harmonic generation|doubled]], [[third-harmonic generation|tripled]] or quadrupled in frequency to produce 532&nbsp;nm (green, visible), 355&nbsp;nm and 266&nbsp;nm ([[ultraviolet|UV]]) beams, respectively. Frequency-doubled [[diode-pumped solid-state]] (DPSS) lasers are used to make bright green laser pointers.

[[Ytterbium]], [[holmium]], [[thulium]], and [[erbium]] are other common "dopants" in solid-state lasers.<ref>{{Cite book |url=https://books.google.com/books?id=tygEGtu1b7MC&q=%C2%A0Ytterbium,+holmium,+thulium,+and+erbium+are+other+common+%22dopants%22+in+solid-state+lasers |title=Handbook of Optics, Third Edition Volume V: Atmospheric Optics, Modulators, Fiber Optics, X-Ray and Neutron Optics |last1=Bass |first1=Michael |last2=DeCusatis |first2=Casimer |last3=Enoch |first3=Jay |last4=Lakshminarayanan |first4=Vasudevan |last5=Li |first5=Guifang |last6=MacDonald |first6=Carolyn |last7=Mahajan |first7=Virendra |last8=Stryland |first8=Eric Van |date=2009-11-13 |publisher=McGraw Hill Professional |isbn=978-0-07-163314-7 |language=en |access-date=July 16, 2017 |archive-date=February 8, 2023 |archive-url=https://web.archive.org/web/20230208064634/https://books.google.com/books?id=tygEGtu1b7MC&q=%C2%A0Ytterbium,+holmium,+thulium,+and+erbium+are+other+common+%22dopants%22+in+solid-state+lasers |url-status=live}}</ref>{{Page missing|date=January 2024}} Ytterbium is used in crystals such as Yb:YAG, Yb:KGW, Yb:KYW, Yb:SYS, Yb:BOYS, Yb:CaF<sub>2</sub>, typically operating around 1020–1050&nbsp;nm. They are potentially very efficient and high-powered due to a small quantum defect. Extremely high powers in ultrashort pulses can be achieved with Yb:YAG. [[Holmium]]-doped YAG crystals emit at 2097&nbsp;nm and form an efficient laser operating at [[infrared]] wavelengths strongly absorbed by water-bearing tissues. The Ho-YAG is usually operated in a pulsed mode and passed through optical fiber surgical devices to resurface joints, remove rot from teeth, vaporize cancers, and pulverize kidney and gall stones.

[[Titanium]]-doped [[sapphire]] ([[Ti-sapphire laser|Ti:sapphire]]) produces a highly [[tunable laser|tunable]] [[infrared]] laser, commonly used for [[spectroscopy]]. It is also notable for use as a mode-locked laser producing [[ultrashort pulse]]s of extremely high peak power.

Thermal limitations in solid-state lasers arise from unconverted pump power that heats the medium. This heat, when coupled with a high thermo-optic coefficient (d''n''/d''T'') can cause thermal lensing and reduce the quantum efficiency. Diode-pumped thin [[disk laser]]s overcome these issues by having a gain medium that is much thinner than the diameter of the pump beam. This allows for a more uniform temperature in the material. Thin disk lasers have been shown to produce beams of up to one kilowatt.<ref>C. Stewen, M. Larionov, and A. Giesen, "Yb:YAG thin disk laser with 1 kW output power", in OSA Trends in Optics and Photonics, Advanced Solid-State Lasers, H. Injeyan, U. Keller, and C. Marshall, ed. (Optical Society of America, Washington, D.C., 2000) pp. 35–41.</ref>