Pseudo-Fourier modal analysis of two-dimensional arbitrarily shaped grating structures.
The pseudo-Fourier modal analysis of two-dimensional arbitrarily shaped grating structures is described. It is shown that the pseudo-Fourier modal analysis has an advantage of improved structure modeling over the conventional rigorous coupled-wave analysis. In the conventional rigorous coupled-wave analysis, grating structures are modeled by the staircase approximation, which is well known to have inherent significant errors under TM polarization. However, in the pseudo-Fourier modal analysis, such a limitation of the staircase approximation can be overcome through the smooth-structure modeling based on two-dimensional Fourier representation. The validity of the claim is proved with some comparative numerical results from the proposed pseudo-Fourier modal analysis and the conventional rigorous coupled-wave analysis.