1 × 3 ultra-wideband photonic crystal waveguide power splitter designed by the downhill simplex algorithm

An ultra-wideband 1×3 beam splitter based on a two-dimensional photonic crystal waveguide is proposed. Different splitting ratios can be achieved by optimizing the radii and offsets of six control dielectric rods. To improve optimization efficiency and splitting performance, the downhill simplex optimization algorithm is used to inverse-design the ultra-wideband 1×3 photonic crystal beam splitter structure. The results show that 1×3 ultra-wideband beam splitters with different splitting ratios can be achieved, including equal-power splitters and unequal-power splitters, even large-splitting-ratio splitters. The operating bandwidth exceeds 70 nm, and the total transmission rate exceeds 96%, with a mean square error of less than 4.88×10^-4 and a response time within 0.8 ps. The beam splitter has a wide operating bandwidth, and high total transmission rate, indicating promising application prospects in future all-optical communication networks and high-density photonic integration.