Types of Lasers

Abstract

The availability of coherent light sources has revolutionized atomic, molecular, and optical science. Since its invention in 1960, the laser has become the basic tool for atomic and molecular spectroscopy and for elucidating fundamental properties of optics and optical interactions with matter. The unique properties of laser light have found many practical applications as well, and the laser has become an essential component of industries such as telecommunications, manufacturing, medicine, and photonics. The various types of lasers can be categorized in a number of different ways; for example, in terms of spectral range, temporal characteristics, pumping mechanism, or by the phase (solid, liquid, gas, plasma) of the laser gain medium. In keeping with a handbook on atomic, molecular and optical physics, the types of lasers will be organized here more fundamentally, according to the type of quantum states involved in the lasing transition. Lasing can arise, for example, from transitions between quantum states that are primarily associated with either a single atom, a single molecule, or an extended solid. But it can also arise from stimulated scattering and nonlinear parametric processes that do not require population inversion between the energy levels of a medium.