Abstract

Since the developent of the Ti³*:Al,O₃ laser (tunable in the 700nm - 1000nm range) much research has been done on tunable solid-state lasers for shorter neighbouring wavelengths. However, non of them has yet been successful, mostly because of strong excited state absorption at the pump or laser wavelength. An interesting candidate for an active laser center in the spectral range below 700nm is the Mn³⁺ ion. The crystal field splitting of its energy levels (in cubic approximation) is described by the Tanabe-Sugano diagram for the d⁴ electron condigurations, shown in Fig. 1. Although for a d⁴ electron system a large number of energy levels exists, only two of them are quintet states, ie the ⁵E group state and ⁵T₂ excited state. Excited state absorption transitions from the ⁵T₂ into higher lying levels are expected to cover a broad wavelength range; but all of these transitions are spin-forbidden, ie the excited state absorption cross section is much smaller than the emission cross section of the ⁵T, —> ⁵E transition. However, in this paper it will be shown, that excited state transistions from other metastable levels prevent laser action in Mn³⁺:Y₃Al₅O₁₂(YAG).

© 1996 Optical Society of America