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.
