Research on Frequency Conversion in Nonlinear Optical Heterostructures

1.半导体异质结构的非线性光学性质我们用Maker条纹技术和反射二次谐波椭圆偏振法测量了GaAs、AlGaAs、GaP、AlGaP、ZnSe和CdTe的非线性光学系数。对Si（100）衬底上生长的GaP和3C-SiC样品进行了表征。离子注入GaP晶体的非线性光学系数仅为GaP单晶的10%。我们还发现3C-SiC/Si的宏观非线性光学系数由于其反相畴结构而消失。2.有机异质结构波导器件发展了一种新的有机晶体/聚合物异质结构波导的制备方法。使用DMNP或MBANP作为非线性光学晶体和聚酰亚胺作为SHG非活性聚合物。我们研制了准相位匹配的有机异质结波导二次谐波器件。二次谐波实验表明，在有机异质结器件中实现了准相位匹配。3.宽带准相位匹配我们提出了一种利用模拟退火算法实现宽带准相位匹配的优化方案。本文报道了准相位匹配铌酸锂波导中宽带二次谐波的产生。

1.NLO Properties of Semiconductor HeterostructuresWe have measured nonlinear optical coefficient of GaAs, AlGaAs, GaP,AlGaP,ZnSe, and CdTe by the Maker-fringe technique and the reflected second-harmonic ellipsometry. Ga-ion-implanted GaP and 3C-SiC grown on Si (100) substrate have been also characterized. Nonlinear optical coefficient of the ion-implanted GaP has been proved to only 10% of that of GaP single crystal. We have also shown that macroscopic nonlinear optical coefficient of 3C-SiC/Si vanishes because of its anti-phase domain structure.2.Organic Heterostrucure Waveguide DeviceA new fabrication method of organic-crystal/polymer heterostructure waveguides has been developed. Using DMNP or MBANP as a nonlinear optical crystal and a polyimide as an SHG-inactive polymer. we have fabricated organic heterostructure waveguid SHG devices for quasi phase matching. SHG experients have shown that quasi phase matching has been achieved in the organic heterostrucure device.3.Broad-Band Quasi Phase MatchingWe have developed a optimization scheme of the broad-band quasi phase matching by simulated annealing. Broad-band second-harmonic generation in quasi-phase-matched LiNbO_3 waveguide has been demonstrated.