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 $$\:1.88\:\lambda^{2}$$ ( $$\:\lambda\:\:=\:1550\:nm$$ ), while maintaining high transmission uniformity within an operating bandwidth of $$\:1480-1565\:nm$$ and minimal mode mismatch. Nearly equal power splitting is achieved with output arms separated by $$\:90^\circ\:$$ . After gradient-based refinement, the splitter reaches a total transmission efficiency of $$\:90.6\%$$ , with insertion and radiation losses of only $$\:3.75\%$$ and $$\:5.65\%$$ , respectively. This paper constitutes the first reported demonstration of three-way power splitting under sharp bending within a sub- $$\:2\:\lambda^{2}$$ footprint in a low index-contrast ( $$\:\epsilon_{r}\:\approx\:\:4.0$$ ) 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.