Optical black-hole analog in inhomogeneous photonic lattice

Hawking radiation, a key to quantum gravity, has stimulated extensive theoretical and experimental studies of various black-hole analogs. Here we theoretically develop a new laboratory analog of black hole in an inhomogeneous two-dimensional graphyne-like topological photonic lattice. A predesigned lattice transition from type-II to type-I Dirac cone creates an analogous curved space time crossing the event horizon (type-III Dirac cone). Photons tunneling through the horizon emit a spectrum of Hawking radiation with a Hawking temperature of 14 μK. Our approach provides a universal design for the optical black-hole analogs in topological photonic crystals and metamaterials.