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Space-Periodic Modulation Model of Piezoelectric Polarization Due to Photorefractive Internal Field for Generation of Nonlinear Vibration

Strong nonlinear behavior was observed in a LiNbO3:Fe piezoelectric resonator with a photorefractive space-periodic grating. The mechanism of the phenomena is considered in terms of a one-dimensional model in which space-periodic electric charges are related to each other. Two vibrational modes of charges, an in-phase vibration and an antiphase one, are considered in this model. The antiphase vibration can be caused by space-periodic modulation of piezoelectric polarization due to a photorefractive internal field. Only the antiphase vibration contributes to the nonlinear phenomena. Transfer of the energy between the two modes is important for understanding the phenomena.