Theory and experiment of diffraction by surface relief gratings with TE and TM polarized incident waves

Abstract

Surface-relief gratings have been made by electron beam evaporation of aluminum on ZnSe and ZnS substrates. Contact photolithography is used to fabricate gratings with a grating period of 3 μm with linewidth resolution down to 0.5 μm. High-quality surface relief structures are then produced by reactiveion etching. The rigorous coupled-wave theory is used to model the diffraction response of the gratings with TE and TM polarized incident waves. Diffraction efficiency measurements have been made at discrete laser wavelengths in the visible region for both polarizations. In addition, the efficiencies have been measured under continuous spectral variation by using a monochromator with output in the visible and near infrared spectral regions. The experimental and theoretical results are compared. Improved agreement is obtained by varying the grating thickness and grating width slightly around the measured nominal values.