  Most applications of metasurfaces require excitation and control of both
electric and magnetic surface currents. For such purpose, the metasurface must
have a finite thickness to handle magnetic surface currents. For metasurface
sheets of negligible thickness that offer only electric response, coherent
illumination can compensate the need to create discontinuities of the
tangential electric field component using magnetic surface currents. Most of
known coherent metasurfaces are space-uniform and can control only plane-wave
absorption and specular reflection. However, it is also known that periodical
space-modulated (inhomogeneous) metasurfaces can be used to realize anomalous
reflection, refraction, and other useful effects. In this paper, we propose the
concept of a coherently-illuminated space-modulated metasurface that functions
as a coherent asymmetric absorber. We study its behaviour under non-ideal
illuminations and suggest applications related with sensing.

Applied Physics;Optics