Rigorous coupled-wave analysis for practical planar dielectric gratings: 1 Thickness-changed holograms and some characteristics of diffraction efficiency

Abstract

A new and useful method for obtaining diffraction efficiencies from holograms manufactured practically is presented. Applying the rigorous coupled-wave analysis, we express each difference between the practical and the ideal as a mathematical component that can be easily integrated. In Part 1 the effects due to thickness change in the hologram layer (observed frequently after the development process) are treated. Although uniform swelling or shrinking causes a simple reconstruction wavelength or incidence-angle shift, nonuniform thickness extends the capacity of the Bragg condition matching, creating a diffraction efficiency curve in the asymmetric profile. Other characteristics of diffraction are also maintained. A refractive-index change has an effect that is similar to the thickness change. Higher-order terms in permittivity modulation create negligible effects in general holograms when used at or near the simple first-order Bragg condition.