Illumination of a photorefractive iron-doped barium-calcium titanate crystal (Ba0.77Ca0.23TiO3, BCT) with an oscillating interference pattern generates oscillating photo currents. These non-steady-state photocurrents arise from the interaction of a space-charge field with a vibrating photoconductivity pattern. However, a second harmonic signal of the oscillating photocurrents is observed in BCT, which is present without any space-charge field. The main features of the new effect can be explained by assuming that a dynamic, i.e. time-dependent, bulk photovoltaic effect exists.
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