{'fraction_non_alphanumeric': 0.016597510373443983, 'fraction_numerical': 0.019363762102351315, 'mean_word_length': 5.033333333333333, '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}}
Investigation on dark decay of two-color holograms in near-stoichiometric LiNbO3 and LiTaO3

We have investigated the dark decay mechanism by measuring dark decay time constants of two-color holograms recorded in undoped and slightly doped near-stoichiometric LiNbO3 and LiTaO3 crystals in the temperature range from 50 to 200 °C. All the samples in this work obey an Arrhenius-type dependence of time constant on absolute temperature, and yield nearly same activation energies of 1.08 eV. The results show that proton compensation mechanism dominated the dark decay process. Lifetimes of holograms at room temperature in LiTaO3 are one order of magnitude longer than that in LiNbO3 if having the same proton concentration.