Conical Anisotropic Grating Diffraction Efficiency Calculation
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Solution Overview
Problem
Current technologies face challenges in achieving high diffraction efficiency and precise parameter determination for anisotropic-material-based gratings, particularly in augmented reality displays where total internal reflection and multiple diffraction orders complicate the analysis.
Innovation Solution
A method involving the calculation of a target geometric phase and slow axis azimuth angle for an anisotropic-material-based grating, coupled with the application of a permittivity tensor in Maxwell's equations, to obtain the diffraction efficiency and parameters of the grating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional diffraction analysis methods are used for anisotropic-material-based gratings, then the analysis can be performed with standard approaches, but the diffraction efficiency calculation lacks precision and parameter determination is inaccurate
Solution Approach 1:
The patent transforms the physical parameters of the anisotropic grating into a mathematical representation by obtaining a permittivity tensor from geometric phase and slow axis azimuth angle. This parameter transformation enables precise diffraction efficiency calculation by applying the tensor to Maxwell's equations, resolving the contradiction between measurement precision and analysis complexity.
Solution Approach 2:
The patent introduces a permittivity tensor as an intermediary mathematical object that bridges the physical grating structure and the electromagnetic field analysis. This tensor serves as a mediator that encapsulates the anisotropic material properties, allowing accurate diffraction efficiency calculation without directly solving complex boundary value problems.
2Manufacturing precision
If geometric phase and slow axis azimuth angle calculations are performed to determine grating parameters, then precise parameter determination is achieved, but the computational process becomes more complex
Solution Approach 1:
The patent performs preliminary calculations of geometric phase and slow axis azimuth angle before applying the permittivity tensor to Maxwell's equations. By pre-determining these critical parameters, the method enables accurate grating parameter determination while organizing the computational process into manageable sequential steps, reducing overall computational complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables the precise calculation of diffraction efficiency and parameter determination for anisotropic-material-based gratings, enhancing the performance of augmented reality displays by improving light control and efficiency.
Implementation Method 1
rays from the displays incident on an input coupler grating (ICG) are diffracted by the ICG, undergo total internal reflection (TIR) within the waveguide (WG), and are finally diffracted out of the WG by an output coupler grating (OCG)
Implementation Method 2
rays from the displays incident on an input coupler grating (ICG) are diffracted by the ICG
Data Source
AI summary
A method of conical anisotropic rigorous coupled wave analysis for grating and a computing device are disclosed. The method includes: obtaining a target geometric phase δ′g for the anisotropic-material-based grating; obtaining a slow axis azimuth angle ϕc(x) of the anisotropic-material-based grating according to the target geometric phase δ′g; obtaining a permittivity tensor of the anisotropic-material-based grating, wherein the anisotropic-material-based grating has an ordinary index no 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 the permittivity tensor into Maxwell equations; obtaining electromagnetic field for the anisotropic-material-based grating by using boundary conditions of at least two layers or sublayers of the anisotropic-material-based grating to obtain a diffraction efficiency for the anisotropic-material-based grating.