We then measured the transmission along Γ-M (propagation along the lattice vector) using a parallel plate waveguide apparatus and observed a ~40 dB dip in the spectrum at ~14. 35 GHz corresponding to the topological band gap, in agreement with high-speed FDTD simulation (Figure ). The interface between the topological and trivial structures supports a topological edge state which bridges the band gap. The interface between our topological and trivial structures is depicted in Figure with the electric field (Ez) distribution of the topological edge state overlaid, and the corresponding band structure is shown in Figure with the edge states shown in red. These edge states are topologically protected against backscattering from defects which preserve the angular momentum of the wave and should thus navigate sharp turns in the interface. Figure shows a bent "omega" waveguide, with the corresponding topological edge states navigating a Z-shaped turn without loss. Indeed, experimental transmission measurements show high transmission across the entire band gap region, with comparable transmission for the straight and bent waveguides, indicative of topological protection and in excellent agreement with high-speed FDTD simulations (Figure ). This constitutes the first experimental example of a fully polymeric photonic topological insulator.