High-order quasi–phase-matching harmonic generation in two-dimensional orthorhombic lattice

The effective high-order quasi–phase-matching second- and third-harmonic generations were realized in a two-dimensional periodically poled \chem{LiNbO_3} with rectangular lattice. The output spots lay at different symmetric places with respect to the input beam of picosecond pulse and the relative intensities of spots at some certain wavelengths were measured. The experimental and theoretical results are in good agreement. Our studies might be beneficial to the development of optics integration and compact devices