Application of Kogelnik's two-wave theory to deep, slanted, highly efficient, relief transmission gratings

Deep photoresist gratings, slanted as well as unslanted, were produced holographically in clear Shipley 1400 photoresist. The diffraction efficiencies of these gratings were measured as a function of incident angle for three wavelengths with polarization perpendicular to the plane of incidence. It is shown that the results agree fairly well with those predicted by Kogelnik's two-wave theory, indicating that these relief gratings behave like volume holograms. An explanation in terms of thin and thick gratings is given, and practical conclusions are drawn from these observations.