A solid state laser in which the active medium is composed of ionic species supported in a crystalline host. The first laser used a ruby crystal in which chromium ions as the active medium were supported in an aluminium oxide (sapphire) crystal. One of the most common crystal lasers involves neodymium atoms in a yttrium aluminium garnet host crystal (the YAG:Nd laser).
Source:
PAC, 1995, 67, 1913. 'Nomenclature, symbols, units, and their usage in spectrochemical analysis-XV. Laser-based molecular spectroscopy for chemical analysis - laser fundamentals (IUPAC Recommendations 1995)' on page 1920 (https://doi.org/10.1351/pac199567111913)