Structural and optical characterization for vapor-phase proton exchanged lithium niobate waveguides

D. H. Tsou, M. H. Chou, P. Santhanaraghavan, Y. H. Chen, Y. C. Huang

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


We have studied the crystalline phase transition for vapor-phase proton exchanged (VPE) lithium niobate waveguide by using pure benzoic acid. The VPE layers in the z-cut lithium niobate crystal have been characterized by X-ray rocking curves, OH- bond infrared absorption, and prism coupling measurements. The crystalline quality assessment by the X-ray rocking curve measurement shows desirable κ2 phase formation for nonlinear optical waveguide applications. It has been observed that the crystalline phase makes a transition from the κ2 to the β phase with the increase in the vapor-phase exchange time. The prism coupling measurement also showed a step-like index profile for our VPE samples. From the step index profile, we deduced an effective diffusion coefficient of 0.14 μm2h-1, which is twice than that of the previously reported value. Shift in the OH- bond absorption wavelength with crystalline phase change and the increase in absorption with the exchange time were also observed from our spectrophotometer measurement.

Original languageEnglish
Pages (from-to)474-479
Number of pages6
JournalMaterials Chemistry and Physics
Issue number2
StatePublished - 17 Feb 2003


  • Lithium niobate
  • Vapor-phase
  • Waveguide


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