Increase of spatial coherence by subwavelength metallic gratings

We study the coherence changes in partially coherent beams transmitted through binary metallic gratings. The interaction of Gaussian Schell-model beams with grating structures supporting surface plasmons is rigorously modeled using the Fourier modal method and the coherent mode representation of partially coherent fields. Our numerical results show that, by choosing suitable parameters for the grating, the degree of coherence of the beam can be significantly increased. The studied approach offers new possibilities to alter the coherence properties of fields using nanophotonic components.