Three-dimensional write-read-erase memory bits by femtosecond laser pulses in photorefractive LiNbO3 crystals

We report on a three-dimensional single-shot optical recording by 150 fs pulses at 800 nm wavelength in Fe-doped and stoichiometric undoped LiNbO3. The highest refractive index modulation of ∼10−3 per single pulse has been achieved at close to the dielectric breakdown irradiance of ∼TW/cm2, and was found to be independent of polarization of the writing beam. The quasi-permanent and rewritable bits have been demonstrated in Fe-doped LiNbO3. Recording in undoped stoichiometric LiNbO3 was of transient nature with full optical contrast recovery on a 0.1-1 s scale. The observed refractive index modulation is explainable by the photovoltaic effect in LiNbO3