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

Excited state absorption (ESA) spectra at room temperature of Mn5+-doped Li,PO, crystals are reported. A broad and strong (sigma(ESA) approximate to 1 x 10(-18) cm(2)) ESA band due to the (1)E --> T-1(1) and (1)E --> T-1(2) 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 Sr-5(VO4)(3)F:Mn5+. This is due to the higher crystal field strength Delta and the weaker distortion of the host tetrahedron in Li3PO4. Finally, the laser potential of Mn5+-doped materials, in general, is evaluated.