  We show that corrugated surfaces of hyperbolic metamaterials scatter light
preferentially inside the media, resulting in a very low reflectance and
ultimate dark appearance in the spectral range of hyperbolic dispersion. This
phenomenon of fundamental importance, demonstrated experimentally in arrays of
silver nanowires grown in alumina membranes, originates from a broad-band
singularity in the density of photonic states. It paves the road to a variety
of applications ranging from the stealth technology to high-efficiency solar
cells and photodetectors.
