Achievement

Much effort has been devoted in the recent past to the design and fabrication of metamaterials (MM) with negative refractive index. Such materials have the potential, as in the form of superlenses, to overcome the diffraction limit in imaging or to enable novel optical effects, including cloaking. Tuning of the MM optical response at visible frequencies is essential to realize these applications. We demonstrated this control on bulk MM obtained by replicating a block copolymer self-assembled morphology into Au, using three different methods. In the first, the structural dimensions of the mesoscopic unit cell were controlled by varying the molecular weight of the structure-forming block copolymer. In the two other strategies using post-processing, tuning was achieved by controlling the metal filling fraction of the plasmonic structure or by filling different refractive index media into the metal scaffold. These results show agreement with finite difference time domain calculations.