Zeroth-Order Complex-Amplitude Modulation by Lamellar Surface Profiles

In diffractive optics phase-only elements provide the highest diffraction efficiencies, but they also generate noise in the neighborhood of the signal window W. Moreover, this noise tends to be strongest in the immediate neighborhood of W. In many applications, such as space-invariant optical interconnection, one must suppress the noise from some given spatial-frequency frame around W. This can be accomplished with a phase-only modulating element, but it requires an effective increase of the size of W to include also the frame. Consequently the numerical complexity of performing the design increases considerably.