POLARIZED AND TIME-RESOLVED MEASUREMENTS OF EXCITED-STATE ABSORPTION AND STIMULATED-EMISSION IN TIYALO3 AND TIAL2O3

Pump-induced excited-state absorption (ESA) in the whole range of pump wavelengths prevents effective laser action of Ti:YAlO3. The time-resolved measurement of this absorption allows the separation of excited-state absorption and losses due to transient colour centres. The influence of polarization on the ESA of Ti:YAlO3 is only weak, as it is expected for a charge-transfer transition. No significant stimulated emission (SE) could be measured in the whole fluorescence region. In comparison, Ti:Al2O3 shows a broad SE spectrum corresponding to the tuning range of this laser material. The strongest SE was measured for E parallel-to c, which is the preferred polarization for laser action of Ti:Al2O3. Below 350 nm the long-wavelength edge of an ESA band was found.