Experimental observation of optical Weyl points and Fermi arcs

We present the experimental observation of type-II optical Weyl points and corresponding Fermi arcs in a three-dimensional photonic structure. We employ a system composed of an array of staggered helical waveguides fabricated using the direct laser writing technique. Weyl points are established by observing conical diffraction and Fermi arcs are demonstrated by showing surface confinement (and deconfinement) at wavelengths above (below) the Weyl point.