In this letter, we investigate the terahertz (THz) electro-optic Kerr effect (KE) dynamics in LaAlO3 (LAO), a widely used substrate for thin film preparation. We show that the KE dynamics strongly depend on the material anisotropy due to interference between THz field-induced and strain-induced optical birefringence. Such interference leads to quasi-phase matching conditions of the KE, which becomes strongly frequency dependent. Depending on the THz frequency, the KE exhibits a uni- and bipolar shape of the quadratic response. The demonstrated effects will be present in a wide variety of materials used as substrates in different THz-pump laser-probe experiments and need to be considered in order to disentangle the different contributions to the measured ultrafast dynamic signals.
@article{arxiv.2501.04346,
title = {Terahertz electro-optic Kerr effect in LaAlO3},
author = {Sergey Kovalev and Changqing Zhu and Anneke Reinold and Max Koch and Zirui Wang and Patrick Pilch and Ahmed Ghalgaoui and Siyu Duan and Cong Li and Jianbing Zhang and Pu Yu and Zhe Wang},
journal= {arXiv preprint arXiv:2501.04346},
year = {2025}
}