Method of conical anisotropic rigorous coupled wave analysis for grating and computing device

A method of obtaining a diffraction efficiency of an anisotropic-material-based grating having at least two layers or sublayers in augmented reality (AR)/virtual reality (VR) devices, comprising:

• obtaining, by a processor, a target geometric phase δ′g for the anisotropic-material-based grating;
• obtaining, by the processor, a slow axis azimuth angle ϕc(x) of the anisotropic-material-based grating according to the target geometric phase δ′g;
• obtaining, by the processor, a permittivity tensor of the anisotropic-material-based grating, wherein the anisotropic-material-based grating has an ordinary index n, and an extraordinary index ne, the anisotropic-material-based grating has a slow axis polar angle θc and slow axis azimuth angle ϕc(x), and the permittivity tensor is based on no, ne, θc and ϕc(x);
• applying, by the processor, the permittivity tensor into Maxwell equations;
• obtaining, by the processor, electromagnetic field for the anisotropic-material-based grating by using boundary conditions of the at least two layers or sublayers of the anisotropic-material-based grating and Maxwell equations for each layer or sublayer, to obtain the diffraction efficiency for the anisotropic-material-based grating,
• determining if the at least two layers or sublayers are suitable to be integrated into one stack for an output coupler grating or an input coupler grating of a waveguide in the augmented reality/virtual reality devices based on the diffraction efficiency;
• and
• analysing the diffraction efficiency by a color dispersion and light control within the augmented reality/virtual reality devices.