Fast Fourier factorization method applied to modal analysis of slanted lamellar diffraction gratings in conical mountings

A new formulation of the Fourier modal method that applies fast Fourier fac torization [J. Opt. Sec. Am. A 17 (2000) 1773] is presented for slanted lam ellar gratings in conical mountings. A new eigenvalue problem in the gratin g region is derived, and used to study metallic gratings. Comparison of the convergence speed of the numerical results given by the conventional metho ds and the new one shows a spectacular improvement. The fast Fourier factor ization method can be also applied to various volume slanted-fringe grating s with discontinuous permittivity variations. (C) 2001 Elsevier Science B.V . All rights reserved.