We propose a new, to our knowledge, method for determining the two main critical parameters of periodic one-dimensional lamellar structures, namely, linewidths and etched depths. The method is simple and requires only two measurements for the phase of the zero-transmitted order under two orthogonal polarizations. It is inspired by the analogy between subwavelength gratings and anisotropic homogeneous thin films. The method is tested with experimental data obtained with a Mach–Zehnder interferometer. Etched depths and linewidths derived from the interferograms and electromagnetic theory are compared with scanning-electron-microscope observations.
© 1999 Optical Society of America
(050.1380) Diffraction and gratings : Binary optics
(050.1950) Diffraction and gratings : Diffraction gratings
(050.1970) Diffraction and gratings : Diffractive optics
(290.3200) Scattering : Inverse scattering
Philippe Lalanne, P. Pichon, P. Chavel, E. Cambril, and H. Launois, "Interferometric Characterization of Subwavelength Lamellar Gratings," Appl. Opt. 38, 4980-4984 (1999)