EXCITED-STATE ABSORPTION-MEASUREMENTS AND LASER POTENTIAL OF CR4+ DOPED CA2GEO4

Polarized continuous wave excited state absorption (ESA) measurements on Cr4+ doped Ca2GeO4 in the 450-2000 nm spectral region at room tempe rature are presented. Weak ESA bands due to the T-3(2) --> T-3(1)(F) t ransition are observed between 1200 and 2000 nm and stronger ESA bands due to T-3(2) --> T-3(1)(P) peak below 1200 nm. The overlap of the T- 3(2) --> T-3(1)(F) ESA band with the emission which extends from 1100 to about 1600 nm will significantly affect the laser performance of Cr 4+ doped Ca2GeO4. The effective peak stimulated emission cross section at 1350 nm in E parallel to b polarization is only about 3 x 10(-20) cm(2). However, our results indicate that tunable laser action between 1300 and 1500 nm should, in principle, be possible.