Definition and classification of solid-state lasers
A laser that uses a solid laser material as a working substance. In 1960, the ruby u200bu200blaser invented by T.H. Mailman was a solid-state laser and the first laser in the world. The solid-state laser is generally composed of laser working material, excitation source, condensing cavity, resonator mirror and power supply.
The solid working material used in this type of laser is made by mixing metal ions that can produce stimulated emission into the crystal. There are three main types of metal ions that can produce stimulated emission in solids:
(1) Transition metal ions (such as Cr3+);
(2) Most lanthanide metal ions (Such as Nd3+, S2+, Dy2+, etc.);
(3) Actinide metal ions (such as U3+).
The main characteristics of these metal ions doped into the solid matrix are: relatively wide effective absorption band, relatively high fluorescence efficiency, relatively long fluorescence lifetime and relatively narrow fluorescence spectrum, Therefore, population inversion and stimulated emission are prone to occur. The artificial crystals used as crystal matrix mainly include: corundum (AL2O3), yttrium aluminum garnet (Y3Al5, O12), calcium tungstate (CaWO4), calcium fluoride (CaF2), etc., as well as yttrium aluminate (YAlO3), beryllium Lanthanum acid (La2Be2O5) and so on. The main glass substrates are high-quality silicate optical glass, such as the commonly used barium crown glass and lime crown glass. Compared with the crystal matrix, the main feature of the glass matrix is u200bu200bthat it is convenient to prepare and easy to obtain large-size high-quality materials. The main requirements for crystals and glass substrates are: easy to incorporate luminescent metal ions for activation; good spectral characteristics, optical transmittance characteristics and high optical (refractive index) uniformity; physical properties suitable for long-term laser operation And chemical properties (such as thermal properties, anti-deterioration properties, chemical stability, etc.). Crystal lasers are typically represented by ruby u200bu200b(Al2O3: Cr3+) and neodymium-doped yttrium aluminum garnet (abbreviated as YAG: Nd3+). Glass lasers are represented by neodymium glass lasers.