Studies on Characteristics of Proton-Exchanged LiNbO3 Optical Waveguides by X-Ray Diffraction and Infrared Absorption Spectroscopy
FU Yun-liang1, 2, HE Meng-xiong2, YUAN Yi-fang3
1. Department of Physics, Hainan Normal University, Haikou 571158, China 2. Department of Chemistry, Hainan Normal University, Haikou 571158, China 3. College of Optics and Electron Information Engineering,University of Shanghai for Science and Technology, Shanghai 200093, China
Abstract：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 LiNbO3 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.
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