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Cascaded parametric downconversion in an aperiodically poled MgO:LiNbO3 superlattice

Quasi-phase-matched parametric downconversion via cascaded optical nonlinearities in an aperiodically poled MgO:LiNbO3 superlattice was studied in theory and experiment. Coupling equations reveal that multiple-wavelength parametric downconversion in a wide infrared spectrum range can occur in a single crystal. Enhancement of the conversion efficiency and output stability through coupling of two nonlinear processes is demonstrated. The result also reveals that cascaded parametric downconversion process can be used to efficiently downconvert the fundamental wavelength to longer wavelength of infrared region.