Monday, November 23, 2015
Abstract-Terahertz response of fractal meta-atoms based on concentric rectangular square resonators
We investigate the terahertz electromagnetic responses of meta-atoms (MAs) induced by different mode coupling mechanisms. Two types of MAs based on concentric rectangular square (CRS) are presented: independent CRS (I-CRS) and junctional-CRS (J-CRS). In I-CRS, each works as an independent dipole so as to result in the multiple resonance modes when the level is above 1. In J-CRS, however, the generated layer is rotated by π/2 radius to the adjacent CRS in one MA. The multiple resonance modes are coupled into a single mode resonance. The level increasing induces resonance modes in I-CRS while in J-CRS. When the level is below 4, the mode Q factor of J-CRS is in between the two modes of I-CRS; when the level is 4 or above, the mode Q factor of J-CRS exceeds the two modes of I-CRS. Furthermore, the modulation depth (MD) decreases in I-CRS while it increases in J-CRS with the increase in levels. The surface analysis reveals that the capacitive coupling of modes in I-CRS results in the modes while the conductive coupling of modes in J-CRS induces the mode A high Q mode with large MD can be achieved via conductive coupling between the of different scales in a MA.