Demonstration of sharp multiple Fano resonances in optical metamaterials

We experimentally demonstrated multiple Fano resonances in optical metamaterials. By combination of two different sized asymmetric-double-bar (ADB) structures, triple Fano resonance was observed in the near-infrared region. In addition to Fano resonance due to anti-phase modes in isolated ADB structures, an anti-phase mode due to coupling among different sized ADBs was observed. Dependence of characteristics of resonances on size difference was also investigated. At specific conditions of size difference, quality factors of three Fano resonances were improved compared with ADB metamaterials consisting of one kind of ADBs. The results will help to realize applications using metamaterial resonators with multiple functionalities and high performance.