Solid State Lasers
Although the first laser demonstrated was a solid state ruby laser, for many years the most common commercial systems were gas lasers such as helium neon lasers and argon ion lasers, or lasers based on organic dyes. Helium neon lasers were frequently limited in output power, argon ion lasers required expensive, sophisticated power supplies and cooling sources, and the dyes used in dye lasers were messy and often toxic. In the past decade, solid state lasers and diode lasers have become the dominant players in the commercial marketplace.
In a solid state laser, the active species is distributed throughout a solid, usually crystalline, material, although glass can also be used as a host. The lasers are robust and frequently tunable, though heat dissipation can sometimes be an issue. Certain types of solid state crystals, for example neodymium-doped yttrium aluminum garnet (Nd:YAG), can be pumped by diode lasers instead of by other lasers or by flashlamps, which is often the case for other materials. Such diode-pumped, solid state systems are reliable, economical, compact, and easy to operate—in fact, many commercial systems are turnkey, needing only to be plugged in and turned on to operate.
Solid state lasers are available from mid-infrared to ultraviolet wavelengths, and at a variety of output powers. Many solid state lasers are tunable, providing output across a range of wavelengths. Some of the most sophisticated laser systems developed are solid-state-based, including ultrafast systems that produce light pulses just 6 femtoseconds (10-15 seconds) long, and are used to study molecular dynamics. Other uses for solid state lasers include medical applications, materials processing, and remote sensing.
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