National Science Council

Yu-Pin Liao

Way-Seen Wang

Ruei-Chang Lu

Chih-Hua Yang

Rei-Shin Cheng

Shung-Jung Lin

A method is used to fabricate a wide-angle Y-branch polarization splitters on lithium niobate crystal substrate. The Y-branch polarization splitter combines a straight waveguide with a substrate prism type wide-angle waveguide branch. The straight waveguide is a random polarization nickel diffusion waveguide. The branching waveguide is a proton exchanged waveguide. The fabrication technology needs only once of nickel diffusion and once of proton exchange. Due to the inherent property of single polarization for the proton exchanged waveguide, only the extraordinary polarization wave is bent and the ordinary wave remains in the straight waveguide. This results in a polarization splitter with high extinction ratio.

Structure and method for fabricating a wide-angle TE-TM mode splitter

This is a fabrication process for Y-branch nickel/zinc-indiffused polarization splitters on lithium niobate. The fabrication technology needs only two nickel/zinc indiffusions; one at a high temperature and the other at a lower temperature. Nickel/zinc-indiffused waveguides can support single-ordinary, single-extraordinary, and random polarization waves depending on the fabrication process parameters. High extinction ratios can be achieved due to the inherent single-polarization of the waveguides. The splitting ratios of the TE and TM modes are sufficiently high for practical applications.

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Taipei Hsien, Taiwan

Yu-Pin Liao