Excited state absorption measurements and laser potential of Cr4+ doped Ca2GeO4

4+

doped Ca₂GeO₄ in the 450–2000 nm spectral region at room temperature are presented. Weak ESA bands due to the ${}^{3}T{}_{2}\to {}^{3}T{}_{1}(F)$ transition are observed between 1200 and 2000 nm and stronger ESA bands due to ${}^{3}T{}_{2}\to {}^{3}T{}_{1}(P)$ peak below 1200 nm. The overlap of the ${}^{3}T{}_{2}\to {}^{3}T{}_{1}(F)$ ESA band with the emission which extends from 1100 to about 1600 nm will significantly affect the laser performance of Cr⁴⁺ doped Ca₂GeO₄. The effective peak stimulated emission cross section at 1350 nm in E∥b polarization is only about 3×10^-20 cm². However, our results indicate that tunable laser action between 1300 and 1500 nm should, in principle, be possible.