Dresden 2020 – wissenschaftliches Programm

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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 15: Postersession KFM

KFM 15.3: Poster

Donnerstag, 19. März 2020, 16:00–18:30, P2/1OG

Spatially resolved excitation of luminescing self-trapped excitons in lithium niobate — •David Brinkmann, Andreas Krampf, and Mirco Imlau — School of Physics, Osnabrueck University, Barbarastraße 7, 49076 Osnabrueck, Germany

Light-induced luminescence in lithium niobate, LiNbO₃ (LN), is based on the excitation of self-trapped excitons (STE) [Blasse, G. et al. Z. Phys. Chem 57 (1968) doi: 10.1524/zpch.1968.57.3_6.187]. These quasi-particles can be efficiently excited optically by a fs-pulse and recombine radiatively in the blue-green spectral range. Using a spatially modulated light pattern for excitation, i.e., a pump pulse interference pattern, STEs are generated in sharp, spatially separated parts of the crystal. Whereas similar holographic gratings based on the excitation of small polarons have previously only been studied indirectly by diffraction experiments based on the nonlinear change of the refractive index and absorption coefficient caused by the polarons, we can now, for the first time, perform a digital read-out of such gratings via detection of the luminescing STEs by means of a CMOS camera. The impact of these findings both for the analysis of recorded grating patterns, for the transport physics of STEs and for visionary applications in digital holography is discussed. Financial support by the DFG (IM 37/11-1, INST 190/165-1 FUGG) is gratefully acknowledged.