质子交换LiNbO_3光波导的特性研究

Studies on Characteristics of Proton-Exchanged LiNbO_3 Optical Waveguides by X-Ray Diffraction and Infrared Absorption Spectroscopy

采用X射线衍射谱法和红外吸收光谱法对质子交换和退火质子交换LiNbO3光波导的特性进行了研究。研究结果表明:在LiNbO3晶体衬底X射线衍射主峰的左侧出现质子交换LiNbO3光波导的伴峰,则质子交换使光波导层Li1-xHxNbO3的晶格常数比衬底的晶格常数稍大,产生垂直于表面的应变,波导经过退火后,伴峰向主峰靠近,应变减少。质子交换波导中的OH-基团的红外吸收光谱在3 500和3 300 cm-1处存在特征峰,波导经过退火后,3 300 cm-1处的特征峰基本消失,而3 500 cm-1处的吸收强度基本不变。实验还表明,OH-在3 500 cm-1处吸收带的积分面积基本与交换时间的开方呈正比例关系。

The characteristics of proton-exchanged and annealed proton-exchanged LiNbO3 optical waveguides were studied by X-ray diffraction and infrared absorption spectroscopy. The X-ray diffraction experiments show that there are diffraction peaks of Li1-xHxNbO3 on the left of the main peak of the LiNbCh crystal substrate. This result means that the crystal lattice constant of the layer Li1-xHxNbO3 is little larger than that of the LiNbO3 crystal substrate, resulting in a stress. After annealing, the X-ray diffraction peaks of the waveguide layer move towards the main peak of the LiNbO3 crystal substrate, and the stress decreases. The infrared absorption spectroscopy experiments show that there are absorption peaks of OH^- at 3 500 and 3 300 cm^-1, and after annealing, the intensity of the absorption peak at 3 300 cm^-1 decreases or disappears, while the intensity of the absorption at 3 500 cm^-1 remains almost invariable. Experiments also show that the integral area of the absorption at 3 500 cm^-1 is proportional to √te .