Fano-like　coupling　was　investigated　extensively　in　plasmonic　nanostructures,　which　is　based　on　the　interaction　between　the　photonic　and　plasmonic　resonance　modes.　Metallic　photonic　crystals　consisting　of　waveguide　metallic　gratings　are　typical　devices　exhibiting　strong　Fano-coupling　between　waveguide　and　plasmon　resonance　modes.　However,　we　demonstrate　here　that　similar　effects　can　also　be　achieved　in　waveguide　dielectric　grating　structures.　In　this　case,　the　broad-band　strong　optical　extinction　results　from　multifold　diffraction　processes,　instead　of　the　plasmonic　absorption　and　scattering　of　light.　The　diffraction　efficiency　of　the　waveguide　dielectric　gratings　was　tuned　by　changing　the　duty　cycle　through　adjusting　the　exposure　time　in　interference　lithography.　Enhanced　diffraction　efficiency　reduces　the　direct　transmission　while　enhances　the　waveguide　resonance　mode,　leading　to　a　Fano-like　coupling　process.　(C)　2015　Optical　Society　of　America