Ultra-Compact and High Performance Three-Way Optical Power Splitter

This work presents an ultra-compact three-way power splitter designed for photonic integrated circuits using topology optimization driven by a custom-developed genetic algorithm. The proposed approach enables global shape reconfiguration within a confined footprint of only 1.88 λ² (λ = 1550 nm), while maintaining high transmission uniformity and minimal mode mismatch. Nearly equal power splitting is achieved with output arms separated by approximately 90°. After gradient-based refinement, the splitter reaches a total transmission efficiency of 90.6%, with only 3.75% reflection and 5.65% radiation losses. This paper constitutes the first reported demonstration of sharp angle three-way power splitting within a sub-2 λ² footprint in a low index contrast (εᵣ ≈ 4.0) platform (such as Si₃N₄-on-SiO₂) through a single jointly optimized junction region. A minimum feature size of 125 nm ensures full compatibility with standard lithography and current fabrication techniques. This approach therefore offers a robust and fabrication-friendly solution for next generation high density power-divider systems.