A method of making a grating in a waveguide includes forming a waveguide material over a substrate, the waveguide material having a thickness less than or equal to about 100 nanometers (nm). The method further includes forming a photoresist over the waveguide material and patterning the photoresist. The method further includes forming a first set of openings in the waveguide material through the patterned substrate and filling the first set of openings with a metal material.