Engineering of splitting ratio in topological photonic beam splitters leveraging chiral edge states

Topological photonic beam splitters leveraging chiral edge states provide a robust and versatile platform for manipulating light. However, conventional designs typically offer fixed, symmetric power splitting, limiting their functionality in photonic circuits. In this work, we present a strategy to engineer the splitting ratio in such topological beam splitters. By systematically exploring junction geometries, specifically Y-junction and T-junction configurations, and modifying the interface orientation, we demonstrate precise control over power distribution between output ports. We identify a key role played by intervalley scattering at specific interface angles, which enables tunability beyond symmetry constraints. We examine both post-based and slab-based configurations working for different polarizations, confirming the generality of the mechanism. Our results highlight the potential of topological beam splitters for compact and reconfigurable photonic devices.