Two-dimensional Si photonic crystal waveguide branch for 850 nm and 950 nm wavelengths

The waveguide branch plays an important role in integrated photonic circuits by dividing input light into two or more output lights, thereby facilitating optical power distribution and mode selection. Ordinary optical waveguides used in waveguide branches suffer from excessive optical loss and narrow branch angles, limiting their effectiveness in mode selection among other problems. Photonic crystals are constructed by arranging macroscopically homogeneous dielectric (or metallic) materials into periodic arrays, with carefully designed internal defects that provide them with frequency-selective and spatial properties. In this study, a silicon-based wide-angle waveguide branch composed of two-dimensional photonic crystals has been successfully created. The branch is capable of separating two wavelengths of light, namely 850 nm and 950 nm, by adjusting the positions of silicon cylinders in the two-dimensional photonic crystal with the purpose of optimizing optical power at different wavelengths. The silicon-based wide-angle waveguide branch is expected to be employed in multimode optical communication systems. Its utilization will contribute towards the reduction in size and complexity of integrated optical communication systems, while enhancing system reliability.