Slanted Gratings

Slanted gratings have been found to be of advantage in lightguide-based display systems for AR/MR applications. Such gratings often have periods that are comparable to the wavelength. Therefore, rigorous computational methods must be used to evaluate their performance. We show, in accordance with existing examples from literature, how to model slanted gratings with different geometries using the Fourier modal method (FMM) in VirtualLab Fusion. Additionally, customized slanted gratings can be designed with the help of parametric optimization.

Analysis of Slanted Gratings for Lightguide Coupling

LightTrans

Different slanted grating geometries are selected from literature, with varying slant angle, fill factor, and modulation depth, and the diffraction efficiencies are calculated with the Fourier modal method (FMM).

Parametric Optimization and Tolerance Analysis of Slanted Gratings

LightTrans

With the Fourier modal method (FMM) as the kernel on which parametric optimization is then applied, a slanted grating is designed to achieve high diffraction efficiency for coupling light into waveguides. Fabrication tolerances including rounded edges are analyzed.

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