Spectrally exclusive phase masks for wavefront coding.

The use of phase masks is necessary for wavefront coding, and these are often based on optical path differences. However, the optical dispersion constrains the resulting device to operate within a restricted spectral bandwidth. Here we propose to remove this constraint due to sub-wavelength structuration of the surface. The use of spatial and spectral co-localization properties of these structures allows the production of various spectrally exclusive phase masks on the same area.