Regensburg 2025 – wissenschaftliches Programm
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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur
KFM 14: Poster
KFM 14.11: Poster
Mittwoch, 19. März 2025, 17:00–18:30, P1
Two Photon Absorption in Lithium niobate tantalate inspected via z-scan technique — •Niklas Dömer1, Anton Pfannstiel1, Steffen Ganschow2, Mike Pionteck2, Simone Sanna3, and Mirco Imlau1 — 1Inst. Physics, Barbarastr. 7, Osnabrück Univ., Germany — 2Leibniz-Institut für Kristallzüchtung, Max-Born-Straße 2, Berlin, Germany — 3Center for Materials Research J.L.-Univ. Giessen, Heinrich-Buff-Ring 16 , Giessen, Germany
The knowledge of the nonlinear optical properties of polar oxide crystals, such as the two-photon absorption (TPA) coefficient β in lithium niobate (LN), is of significant importance for tailoring technological applications in (integrated) photonics. Here, we present the results of our studies on the dispersion properties β(λ), i.e. the imaginary part of the third-order susceptibility χIm(3), in the model system lithium niobate tantalate (LNT, LiNbxTa1−xO3 with 0≤x≤1). Experimentally, an open-aperture z-scan experiment pumped by fs-pulses in the spectral range of 330 - 600 nm from an optical parametric amplifier (OPA) is used. The obtained results are compared with literature data for LN (x=0) and LT (x=1) and the non-vegard-like behavior of the band gap. In extension, the study is applied for the determination of the density of states with LN as an example. We discuss our findings with ab-initio calculations for LN and in the framework of transient absorption phenomena induced by TPA in LNT [N. Dömer, J. Koelmann et al., New J. Phys. 26 (2024) 083027]. This work is financially supported by the DFG (projects IM37/13-1, GA 2403/7-1 and SA1948/3-1 within the research unit FOR 5044, ID: 426703838).
Keywords: Two Photon Absorption; Lithium Niobate; Lithium Tantalate; nonlinear optics