H-Tree-Type Optical Clock Signal Distribution Circuit Using a Si Photonic Wire Waveguide

We fabricated an ultra small H-tree-type optical signal distribution circuit on a silicon-on-insulator substrate. We used a micron-size bent-waveguide-type optical branch in a Si photonic wire waveguide and observed clear light output from eight output ports for laser light of 1.5 µm wavelength. The fluctuation of distributed light intensity was 2–5 dB. It was caused by a nonuniform branching ratio, and can be reduced by improving asymmetric corner shapes of each branch.