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arXiv · 2106.01145

Polaronic Enhancement of Second-Harmonic Generation in Lithium Niobate

Agnieszka L. Kozub·Arno Schindlmayr·Uwe Gerstmann·Wolf Gero Schmidt
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Abstract

Density-functional theory within a Berry-phase formulation of the dynamical polarization is used to determine the second-order susceptibility $\chi^{(2)}$ of lithium niobate (LiNbO$_3$). Defect trapped polarons and bipolarons are found to strongly enhance the nonlinear susceptibility of the material, in particular if localized at Nb$_\mathrm{V}$-V$_{\mathrm{Li}}$ defect pairs. This is essentially a consequence of the polaronic excitation resulting in relaxation-induced gap states. The occupation of these levels leads to strongly enhanced $\chi^{(2)}$ coefficients and allows for the spatial and transient modification of the second-harmonic generation of macroscopic samples.

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Agnieszka L. Kozub, Arno Schindlmayr, Uwe Gerstmann, Wolf Gero Schmidt. 2021-06-02. Polaronic Enhancement of Second-Harmonic Generation in Lithium Niobate. https://doi.org/10.1103/physrevb.104.174110

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