采用外加高压电场极化的方法,制备了二维八重准周期结构的铌酸锂非线性光子晶体。沿该晶体倒空间的基矢方向上实现了两种波长的有效共线倍频输出,在偏离该方向22.5°的方向上,获得了另外三种波长的倍频输出。同时,在入射光束对称两侧观察到了不同种波长的非共线倍频光斑。利用二维八重准周期铁电晶体,在约480 nm的入射波长范围内实现了近20种波长的共线及非共线准相位匹配倍频过程,两邻近的基频波长间隔最小可达3 nm。当晶体旋转45°的整数倍时,可以得到相同的结果。

The LiNbO₃ nonlinear photonic crystal with two-dimensional octagonal quasilattice was fabricated by applying external electric field. Along the direction of the basic reciprocal vectors,the effective collinear quasi-phase matching (QPM) second-harmonics (SH) of two wavelengths were realized,and along the direction diverging 22.5° from the former direction,so were three other wavelengths. Simultaneously,the non-collinear QPM SH at two symmetric angles with respect to the input wavelength were observed. The collinear and non-collinear QPM harmonics of about twenty wavelengths were obtained in the range of 480 nm,in which the minimum interval of two adjacent fundamental wavelengths was only 3 nm. The same results could also be obtained by rotating the crystal by 45°.