A sub-wavelength grating device having controlled phase response includes a grating layer having line widths, line thicknesses, line periods, and line spacings selected to produce a first level of control in phase changes of different portions of a beam of light reflected from the grating layer. The device also includes a substrate affixed to the grating layer that produces a second level of control in phase changes of different portions of a beam of light reflected from the grating layer, the second level of control being accomplished abrupt stepping of the substrate in a horizontal dimension, ramping the substrate in a horizontal dimension, or changing the index of refraction in a horizontal dimension.