Excited-state absorption in Ti:YAlO3

Excited-state absorption has been observed at 632.8 nm in Ti:YAlO3 pumped with 532-nm radiation from a frequency-doubled Nd:YAG laser. The samples used in this work were single crystals grown by the unseeded heat exchanger method. Measurements of fluorescence emission, fluorescence lifetime, and absorption were also made. Although these crystals have no detectable parasitic absorption in the wavelength region of the fluorescence emission, the authors were unable to achieve lasing. This may be due to the presence of excited-state absorption in the fluorescence emission band. The authors attribute the excited-state absorption to charge transfer transitions from the 3d excited state of Ti3+ ions to energy levels of unidentified defects