Reducing the Complexity: Enantioselective Chiral Near-Fields by Diagonal Slit and Mirror Configuration

We report an easy-to-fabricate plasmonic design consisting of diagonal slits in a metallic film on top of a mirror for the generation of chiral near-fields of one single handedness. Our numerical investigations show that the distance between the two layers is crucial for the properties of this design. While the far-field response can be used to identify layer distances with strong chiral near-fields, this distance must be small enough to additionally ensure single-handedness of the respective fields close to the slit area. The fields of interest can be easily accessed by chiral molecules because they are located within the slits. Based on this finding, we propose and numerically verify a novel technique for chiroptical spectroscopy in a reflection geometry.