Theory of Weyl-points in Electromagnetic Continua

Recently, Weyl-points have attracted a lot of attention both in electronics and in photonics. In the vicinity of a Weyl point the energy-momentum dispersion is linear and consists of two touching bands. Remarkably, Weyl points are highly robust to any form of perturbation that preserves the Hermitian property of the relevant time evolution operator (the Hamiltonian). Furthermore, a material with Weyl-points supports exotic edge states, known as Fermi arcs, which enable unusual wave phenomena. In this talk, we will present a general and simple criterion to characterize and determine all the Weyl points of a wide class of bianisotropic dispersive electromagnetic continua with no intrinsic periodicity. We apply the developed theory to the case of media invariant under-rotations about some fixed axis, and determine the most general classes of electromagnetic media with Weyl-points. We will present a detailed numerical study that illustrates the robustness of the Weyl points to arbitrary perturbations and illustrates the unusual properties of the considered photonic platforms.