  Photonic topological insulators provide unprecedented possibilities to
eliminate scattering losses and improve the efficiency of optical communication
systems. Despite significant theoretical efforts, the experimental
demonstration of an integrated photonic topological insulator operating in the
telecommunication regime was still missing. Here, we design, fabricate and
characterize a photonic-crystal-based topological structure that exhibits
valley-Hall effect. We experimentally demonstrate the propagation of
topologically protected edge states in a CMOS-compatible chip operating at
telecommunication wavelengths. This contribution is an important step towards
integrated topological photonics.
