Multilayer dielectric diffraction gratings

A method for fabricating a nonmetallic diffraction grating for producing specular reflection and diffracted orders in reflection and transmission, comprising:

• placing a multilayer dielectric stack upon a substrate;
• placing an antireflective or absorbing layer upon the top of said multilayer stack, wherein said layer minimizes the reflectance of light from said multilayer dielectric stack during the step of exposing photosensitive material, wherein said antireflective or absorbing layer comprises a material which is transparent to the wavelength of light at which the grating will eventually be used;
• coating photosensitive (commonly positive or negative photoresist) material on said absorbing layer;
• exposing said photosensitive layer to a periodic pattern of light and dark radiation (the grating pattern);
• developing said photosensitive material to produce a surface relief pattern;
• depositing a plurality of layers of dielectric material upon said surface relief pattern, wherein each layer of said plurality of layers comprise a precise thickness as determined by the required functionality of said nonmetallic diffraction grating, wherein each layer of said plurality of layers comprises either a high refractive index dielectric material or a low refractive index dielectric material, wherein said high refractive index dielectric material and said low refractive index dielectric material comprise a difference in refractive index greater than 0.1, wherein said plurality of layers comprises a top layer and a bottom layer, wherein said bottom layer is affixed to said substrate;
• and
• removing (lift-off) any remaining photosensitive material to produce a completed multilayer dielectric diffraction grating comprising grooves, wherein each groove of said grooves comprises a depth and a shape, wherein said diffraction grating is formed within said top layer of said plurality of layers, wherein the fraction of light incident on the apparatus which undergoes specular reflection, diffraction and transmission is determined by adjusting (i) the number of layers of said plurality of layers, (ii) the thickness of at least one layer of said plurality of layers and (iii) said depth and shape of said grooves wherein each layer of said multilayer dielectric diffraction grating comprises a continuous film, wherein said multilayer dielectric diffraction grating comprises a top layer comprising a diffraction grating.