Valley-Hall (topological)
Domain wall / edge channel
Light pulse
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This simulator renders a honeycomb photonic crystal split into two domains whose rod-size asymmetry has opposite sign, which gives them opposite valley Chern number. The interface between the domains hosts a topologically protected "kink" edge state, and the scene fires light pulses along it — through a sharp 90°-ish bend and past a tunable local defect — to show them pass through with only weak loss. Flip to the conventional line-defect waveguide mode to see the same bend and defect strongly reflect an ordinary, unprotected guided mode. Live readouts track transmission, the edge mode's group velocity, and the valley Chern contrast across the interface.