Editing Tunable laser (section)

===Multi-line tuning===
Most laser gain media have a number of transition wavelengths on which laser operation can be achieved. For example, as well as the principal {{formatnum:1064}}&nbsp;nm output line, Nd:YAG has weaker transitions at wavelengths of {{formatnum:1052}}&nbsp;nm, {{formatnum:1074}}&nbsp;nm, {{formatnum:1112}}&nbsp;nm, {{formatnum:1319}}&nbsp;nm, and a number of other lines.<ref>Koechner, §2.3.1, p53.</ref> Usually, these lines do not operate unless the gain of the strongest transition is suppressed, such as by use of wavelength-selective [[dielectric mirror]]s. If a [[dispersion (optics)|dispersive]] element, such as a [[prism (optics)|prism]], is introduced into the optical cavity, tilting the cavity's mirrors can cause tuning of the laser as it "hops" between different laser lines. Such schemes are common in [[argon]]-[[ion laser]]s, allowing tuning of the laser to a number of lines from the [[ultraviolet]] and [[blue]] through to [[green]] wavelengths.