[Infrared absorption spectroscopy of optical waveguide in proton-exchanged LiNbO3]

Z-cut proton-exchanged LiNbO3 optical waveguides exchanged with different proton sources mixed with adipic acid and benzoic acid in different mol ratios were analyzed by infrared absorption spectroscopy. The result shows that there is an absorption peak of OH- free group at 3500 cm(-1) with the characteristic of substitute protons, and the absorption peak of H-bond is nearby 700 cm(-1) with the characteristic of packing protons. The different mixing ratios and different concentrations of H+ in the proton source, result in different proton-exchanged velocities and bring on the change in these absorption peaks. It is very important to study the change in these absorption peaks for making high quality LiNbO3 optical waveguide.