Thin-Element Approximation vs. FMM/RCWA

As a widely used method in the diffractive optics community, the thin-element approximation (TEA) turns out to be very efficient in the calculation of the diffraction efficiencies of thin diffractive elements. On the other hand, it is also known that such an approximation becomes inaccurate when e.g. the period of the diffractive grating becomes small in comparison to the wavelength. We selected two commonly used profiles for transmission gratings (sinusoidal and blazed), and apply TEA and the rigorous FMM/RCWA for their analysis, in order to compare the results from both methods.

TEA vs. FMM for Grating Modeling

We apply both TEA and FMM (also known as RCWA) to analyze two types of gratings (sinusoidal and blazed) with varying period and compare the results from both methods.

Analysis of Blazed Grating by Fourier Modal Method

The Fourier modal method (FMM) can be used to analyze grating efficiencies rigorously in VirtualLab Fusion.

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Download free trial version