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HL: Fachverband Halbleiterphysik

HL 61: Focus Session: Tailored Nonlinear Photonics I

HL 61.6: Vortrag

Donnerstag, 19. März 2020, 12:00–12:15, POT 51

Quasiparticle and excitonic effects in the lithium niobate polaron optical absorption — •Falko Schmidt, Wolf Gero Schmidt, Arno Schindlmayr, and Uwe Gerstmann — Department Physik, Universität Paderborn, 33095 Paderborn, Germany

Lithium niobate (LiNbO₃), a perovskite-structure ferroelectric, is widely employed in nonlinear optical applications. The material employed in technical applications is usually grown from a congruent melt and therefore characterized by a high concentration of intrinsic defects which influence its optical properties. The latter are usually interpreted within the polaron concept [1]. Polarons tend to localize at crystal defects, especially at positively charged impurities, due to the attractive Coulomb potential and the additional lattice distortion. In the present study we perform many-body perturbation theory calculations in order to determine the influence of electron quasiparticle and electron-hole attraction effects on the polaron optical absorption. By means of comparison between simulated spectra and measured data [1] we are able to propose detailed atomic structures giving rise to both polarons and bipolarons.

[1] OF Schirmer, M Imlau, C Merschjann, B Schoke, J. Phys.: Condens. Matter 21, 123201 (2009).