We present a dynamically reconfigurable topological photonic crystal waveguide in lithium niobate on insulator (LNOI) with a new benchmark \(55{\%}\) electro-optic bandgap tuning and ultralow propagation loss of \(0.10{-}0.29\text{ dB}/\text{cm}\) . Using 3D finite-element method (FEM) simulations with high-order basis functions, we demonstrate a complete photonic bandgap of \(12.3{\%}\) at zero bias, centered at \(194.5\text{ THz}\) . Voltage-dependent tuning shifts the bandgap from \(187.2\) to \(201.9\text{ THz }(0{-}15\text{ V})\) , with linear scaling and \(2.0\text{ ns}\) switching speed. Topological Jackiw–Rebbi edge states enable \(>99.2{\%}\) transmission through \(120^\circ \) bends and \({\text{BER }} < { }10^{ - 12}\) at \(10\text{ Gbps}\) . This platform establishes a new benchmark for reconfigurable topological photonics with applications in optical computing, quantum networks, and adaptive signal routing.
