Yasuhiro HARA, Shin YOKOYAMA^* and Kazutaka UMEDA

Research Center for Nanodevices and Systems, Hiroshima University, 1-4-2 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8527, Japan

(Received May 15, 2003; Accepted July 8, 2003)

We have developed a novel branched optical waveguide using a stacked directional coupler, which consists of two Si₃N₄ core layers (each 0.3 μm thick) stacked with a thin (0.2 μm) SiO₂ film in between. Using this stacked high-index-contrast system, the size of the multiple branched waveguides can be dramatically reduced compared with the conventional Y-shaped branches. A four-branch optical waveguide is designed and fabricated, and good performance of distribution power of 25 ± 4 % to each branch has been achieved.

Key words: directional coupler, branched waveguide, stack type, high-index-contrast, silicon nitride/silicon oxide, silicon substrate

^*E-mail address: yokoyama@sxsys.hiroshima-u.ac.jp