Mode suppression in a slanted grating

In this paper, we propose a novel method of mode suppression in a slanted grating; this can reveal the physical diffraction mechanism in the grating region. Analytical expressions are derived to illustrate the diffraction process based on the simplified modal method. Owing to the odd mode suppression, only two even grating modes determine the even symmetry field distribution at the output plane. In addition, a slanted grating is designed to make the oblique light mainly couple into the normal emission; this is notably different from a rectangular grating, which can never be used to realize this goal. Numerical simulation results verify the validity of the simplified modal method. We hope that this theoretical work can lay a solid foundation for potential applications of slanted gratings.