Optical transient induced absorption and bleaching as a function of wavelength for reduced SrTiO<sub>3</sub> with a picosecond pump–probe technique have been studied. An energy-level model of the reduced SrTiO<sub>3</sub> is proposed to explain the experimental results. The reduced SrTiO<sub>3</sub> crystal examined has two absorption bands centered at 1.7 eV and 2.4 eV, which are assigned to transitions from levels lying in the band gap approximately 1.5 eV and 0.8 eV above the valence band, respectively, to the conduction band. The relaxation times of electrons from the conduction band to the level at 1.5 eV and from the level at 1.5 eV to the level at 0.8 eV are determined to be ~40 ps and much larger than 500 ps, respectively.
© 1997 Optical Society of America
K. V. Yumashev, P. V. Prokoshin, A. M. Malyarevich, and V. P. Mikhailov, "Transient bleaching/induced absorption in reduced SrTiO3 under picosecond excitation," J. Opt. Soc. Am. B 14, 415-419 (1997)