Application of the beam propagation method to diffused transmission gratings

Abstract

In this paper results for the diffraction characteristics of phase gratings calculated by the beam propagation method and by a rigorous integral equation method are presented, with the latter results serving as a reference. The configurations under consideration have refractive index changes which are realistic for ion exchange processes in glass. Thus, multiple reflections have only little influence which makes the beam propagation method applicable to the problem. Typically, the diffraction efficiencies computed by both methods differ by less than 2%. In contrast to the integral equation method, the beam propagation method works with a definable lateral field profile, enabling the modelling of a grating within a complete device design including the near field pattern.