Low-loss proton-exchanged waveguide in MgO-doped LiNbO/sub 3/ fabricated with pyrophosphoric acid using Ta/sub 2/O/sub 5/ protective mask

The authors describe low-loss proton-exchanged channel waveguides in MgO-doped LiNbO/sub 3/. The authors demonstrate the application of a Ta/sub 2/O/sub 5/ film for the protective mask material in proton-exchanging instead of a Ta film in order to reduce the propagation loss. A Ta/sub 2/O/sub 5/ sputtered film was applied as a protective mask with pyrophosphoric acid. The propagation loss of the waveguide, measured with laser diode light ( lambda =0.83 mu m) was 0.5 dB/cm. It is shown that the use of a Ta/sub 2/O/sub 5/ mask reduces the propagation loss compared with the use of a Ta mask (1.5 dB/cm).<
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