Résumé
We present a dramatic simplification of the, well-known, Fourier Modal Method1 (FMM) equipped with the Adaptive Spatial Resolution2 (ASR) concept for gratings with subwavelength heights. We show that, in this case, it is possible to compute the scattering matrix of the grating by solving only one eigenvalue problem (instead of three or even more) which reduces the most expensive computational part of the FMM-ASR algorithm. This approach is very efficient and thus suitable for periodic metasurfaces.References1. G. Granet and B. Guizal, Efficient implementation of the coupled wave method for metallic lamellar gratings in TM polarization, J. Opt. Soc. Am. A, Vol 13, No 5, pp 1019-1023, May 1996.2. B. Guizal, et al., “Reformulation of the eigenvalue problem in the Fourier modal method with spatial adaptive resolution,” Opt. Lett. 34, N° 18, 2790-2792, 2009.