The dispersion relation of eigenmodes of two-dimensional waveguide gratings is studied with a perturbative model. The analytic expression of the complex wavelength of the modes permits us to predict the shape of the anomalies in the grating reflectivity with respect to the wavelength and the polarization of the incident plane wave. The simultaneous excitation of two independent modes is necessary for obtaining high-efficiency filtering of unpolarized light. We show how this requirement can be met.
© 2003 Optical Society of America
Anne-Laure Fehrembach and Anne Sentenac, "Study of waveguide grating eigenmodes for unpolarized filtering applications," J. Opt. Soc. Am. A 20, 481-488 (2003)