Veselago lensing with Weyl metamaterials

Negative refraction is an exotic optical phenomenon that is usually observed at the interface between a positive-index material and a negative-index, or “left-handed” material. One direct application of negative refraction is the Veselago lens, a flat lens that can focus the light emitted by a point source located on one side of the negative index medium onto the opposite side. Besides negative-index materials, Veselago lensing effect has been observed with two-dimensional crystals possessing Dirac points, such as graphene for electrons. Here we observe all-angle negative refraction and Veselago imaging in three dimensions with a Type I Weyl metamaterial. Furthermore, our ideal Weyl metamaterial exhibits remarkable spin-selective transmission around the Weyl frequency that arises from its intrinsic chiral optical response. Our results show that the ideal Weyl metacrystal provides a versatile platform for lensing applications and novel photon-spin selective devices.