Nested photonic crystals defined by connectivity

We designed and realized nested 3D meta-crystals defined by connectivity. They have scalar-wave-like band dispersions, making the search for photonic topological phases an easier task. Their surface states have skyrmion-like electric field distributions, which have high-Q even inside the light cone continuum. As such, the topological surface states in our 3D nested crystals can be exposed directly to air, making such systems well-suited for practical applications. Our ideas were demonstrated experimentally.