Excited state absorption and laser potential of Mn5+-doped Li3PO4

Excited state absorption (ESA) spectra at room temperature of Mn5+-doped Li3PO4 crystals are reported. A broad and strong (σESA ≈ 1 × 10−18 cm2) ESA band due to the 1E → 1T1 and 1E → 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 Δ and the weaker distortion of the host tetrahedron in Li3PO4. Finally, the laser potential of Mn5+-doped materials, in general, is evaluated.