ruby laser

https://doi.org/10.1351/goldbook.R05427
A pulsed source of coherent radiation emitting mainly at \(\pu{694.3 nm}\) from chromium ions ($\ce{Cr^{3+}}$) in aluminium oxide.
Source:
PAC, 1996, 68, 2223. (Glossary of terms used in photochemistry (IUPAC Recommendations 1996)) on page 2272 [Terms] [Paper]