M. F. Hazenkamp, H. U. Güdel, S. Kück, G. Huber, W. Rauw and D. Reinen
Excited state absorption and laser potential of Mn⁵⁺-doped Li₃PO₄
Chem. Phys. Lett. 265, 264-270 (1997)                 

Abstract: Excited state absorption (ESA) spectra at room temperature of Mn⁵⁺-doped Li₃PO₄ crystals are reported. A broad and strong (s_ESA 1 × 10^–18 cm²) ESA band due to the ¹E ¹T₁ and¹ E ¹T₂ transitions is observed between 10000 and 15000 cm^–1 which prevents efficient near-infrared pumping for laser operation. For Mn⁵⁺-doped Li₃PO₄ there is no ESA at the stimulated-emission wavelength, in contrast to the laser material Sr₅(VO₄)₃F:Mn⁵⁺. This is due to the higher crystal field strength D and the weaker distortion of the host tetrahedron in Li₃PO₄. Finally, the laser potential of Mn⁵⁺-doped materials, in general, is evaluated.