Enhanced sensing performance by the plasmonic analogue of   electromagnetically induced transparency in active metamaterials
  The gain-assisted plasmonic analogue of electromagnetically induced transparency (EIT) in a metallic metamaterial is investigated for the purpose to enhance the sensing performance of the EIT-like plasmonic structure. The structure is composed of three bars in one unit, two of which are parallel to each other (dark quadrupolar element) but perpendicular to the third bar (bright dipolar element), The results show that, in addition to the high sensitivity to the refractive-index fluctuation of the surrounding medium, the figure of merit for such active EIT-like metamaterials can be greatly enhanced, which is attributed to the amplified narrow transparency peak. 
Zheng-Gao Dong, Hui Liu, Jing-Xiao Cao, Tao Li, Shu-Ming Wang,   Shi-Ning Zhu, and Xiang Zhang
physics.optics cond-mat.mtrl-sci