Abstract

In comparison to Ti³⁺-doped sapphire the fluorescence of Ti³⁺:YA103 is shifted into the orange—yellow spectral region with maximum at λ_em ~ 620 nm (see Fig. 1). This makes Ti:YAl₂O₃ very attractive as a tunable solid state laser thus extending the tuning range of Ti:YAl₂O₃ to shorter wavelengths. However, lasing of Ti:YAl₂O₃ was reported by only one research group in 1988 [1] and could not be reproduced until now. Later on it was shown, that excited state absorption (ESA) from the ²E-state of the Ti³⁺—ion to an unknown charge transfer state is decreasing the pumping efficiency strongly [2,3]. Because the strength of the ESA—transition depends on the crystal growth conditions, that is on the growth atmosphere and on codoping, it is believed, that the electron is not excited from the ²E-state into the conduction band but into a neighbouring defect centre. The aim of our work is now, to understand the structure of this complex centre and perhaps to prevent it by suitable crystal growth conditions. The presented photoconductivity measurements in connection with ESA data give us some information about the groundstate of the Ti³⁺–ion and the adjacent defect centre within the YAIO₃ energy gap.

© 1993 Optical Society of America