US Patent 11249230 Duty cycle, depth, and surface energy control in nano fabrication

A surface-relief grating includes a base surface-relief grating comprising a plurality of ridges that include a first material, and a second material on only a top surface or a single sidewall of each ridge of the plurality of ridges, where the second material is different from the first material. A method of fabricating the surface-relief grating includes etching or molding a base surface-relief grating that includes a plurality of ridges, depositing a material layer on the plurality of ridges, and selectively etching the material layer to increase a height or a slant angle of an edge of a ridge in the plurality of ridges to make the surface-relief grating that includes the base surface-relief grating.