{'fraction_non_alphanumeric': 0.01463963963963964, 'fraction_numerical': 0.006756756756756757, 'mean_word_length': 5.304964539007092, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Rearrangement of Rare Earth Defects Under Domain Inversion in LiNbO3

Using high resolution excitation-emission spectroscopy we investigated the changes occurring in the optical transition of Er3☎ ions in LiNbO3 during inversion of the ferroelectric axis. In stoichiometric LiNbO3 we find that a drastic reconfiguration among the different defect sites takes places favoring those centers which have already been dominant in the as-grown sample. The reconfiguration is attributed to changes in the arrangement of the local charge compensators. Furthermore, we find a small shift of the emission transition energy, which is consistent with an increase of the intrinsic electric field. These findings make the Er3☎ ions very suitable probes for 3D imaging of domain structures and for in-situ studies of the dynamics of the domain inversion processes and the defect/domain wall interaction.