Regensburg 2019 – wissenschaftliches Programm
KFM 14.22: Poster
Mittwoch, 3. April 2019, 16:00–18:30, Poster C
Transient absorption in iron-doped lithium niobate induced via tailored optical excitation paths — •David Brinkmann, Simon Messerschmidt, Andreas Krampf, Laura Vittadello, and Mirco Imlau — School of Physics, Osnabrueck University, Barbarastraße 7, 49076 Osnabrueck, Germany
Doping of lithium niobate (LN) with transition metals, e.g. iron, has a strong impact on the optical properties as well as transport dynamics of optically excited charge carriers. The most of these effects were investigated by the technique of light-induced absorption (LIA) and pump-wavelengths in the visible spectral range preferring a charge transfer from Fe2+ to Nb5+ (D-band). In this study, we present LIA data measured under three different, tailored experimental conditions, i.e., a combination of different iron concentrations and Fe2+/Fe3+ ratios in the crystal and an excitation wavelength in the UV spectral range (355 nm), with the aim to excite the sample via a charge transfer from O2− to Fe3+ (C-band) or O2− to Nb5+ (LN band-edge). Our results demonstrate clearly the possibility to alter the induced absorption both in the spectral range and relaxation time by order of magnitudes as a function of the excitation paths. All of our observations can be explained straightforwardly by using the excitation and recombination model proposed by Messerschmidt et al. [J. Phys.: Condens. Matter (2018) doi: 10.1088/1361-648X/aaf4df] which is based on the presence of both, small polarons as well as self-trapped excitons trapped at different lattice positions. Financial support by the DFG (IM 37/5-2, INST 190/165-1 FUGG) is gratefully acknowledged.