Reflection second harmonic generation on a<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>z</mml:mi></mml:math>-cut congruent lithium niobate crystal

Abstract

Reflection second harmonic generation experiments were performed on $z$-cut congruent lithium niobate crystals $(\mathrm{Li}\mathrm{Nb}{\mathrm{O}}_{3})$ to reveal the interfacial layer symmetry as the crystal is rotated around the $z$ axis. To suppress the bulk contribution, the fundamental wavelength was selected to be $532\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$, resulting in second harmonic generation at a wavelength within the absorption region of the crystal. The polarity of the direction of the $y$-axis was determined from second harmonic generation data and used to show that this direction also inverts during domain inversion.