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HL: Fachverband Halbleiterphysik

HL 7: Poster I

HL 7.14: Poster

Montag, 27. März 2023, 13:00–15:00, P2/EG

Excitons in lithium niobate and their impact on non-linear optical properties — •Agnieszka Kozub, Wolf Gero Schmidt, and Uwe Gerstmann — Universität Paderborn, Department Physik, 33095 Paderborn, Germany

The influence of self-trapped and vacancy-trapped excitons on the lithium niobate (LiNbO₃, LN) dielectric function and nonlinear susceptibility is calculated based on density-functional theory. The PBE0 hybrid functional is used for the description of electron exchange and correlation. The dielectric function it obtained by solving the Bethe-Salpeter equation. This yields an absorption peak at 2.6 eV, in perfect agreement with experiment [1]. The second- and third order- nonlinear susceptibility tensors are obtained from a Berry-phase formulation of the dynamical polarization. A strong enhancement of the susceptibilities for photon energies in the band gap region is noted to arise from localized excitons.

[1] L.E. HALLIBURTON, K.L. SWEENEY and C.Y. CHEN, Nuclear Instruments and Methods in Physics Research Bl 344-347 (1984)