  We introduce the concept of non-uniform metamirrors (full-reflection
metasurfaces) providing full control of reflected wave fronts independently
from the two sides of the mirror. Metamirror is a single planar array of
electrically small bianisotropic inclusions. The electric and magnetic
responses of the inclusions enable creating controlled gradient of phase
discontinuities over the surface. Furthermore, presence of electromagnetic
coupling in the inclusions allows independent control of reflection phase from
the opposite sides of the mirror. Based on the proposed concept, we design and
simulate metamirrors for highly efficient light bending and
near-diffraction-limit focusing with a sub-wavelength focal distance.
