Quasi-Cw Ultraviolet Generation in a Dual-periodic LiTaO3 Superlattice by Frequency Tripling

We propose a dual-periodically domain-inverted structure for realizing an efficient third-harmonic generation at an arbitrary fundamental wavelength. The structure allows to couple two separate optical parametric processes, frequency doubling and frequency adding, through a cascaded quasi-phase-matched interaction, therefore, generate third-harmonic directly from a superlattice sample. As an example, we designed and fabricated such a structure in a LiTaO3 crystal. Using a LD pumped 1.064 µm quasi-cw Nd:YVO4 laser as a fundamental source, considerable ultraviolet at 355 nm was generated from this superlattice by frequency tripling. And green at 532 nm was simultaneously obtained by frequency doubling.