Abstract-Novel tunable terahertz graphene metamaterial with an ultrahigh group index over a broad bandwidth

Hui Xu, Hongjian Li, Zhiquan Chen, Mingfei Zheng, Mingzhuo Zhao, Cuixiu Xiong and Baihui Zhang

http://iopscience.iop.org/article/10.7567/APEX.11.042003/meta

We propose a grating-coupled graphene metamaterial structure at a terahertz band. An obvious tunable plasmon-induced transparency can be achieved by changing the graphene Fermi level, and there is a very high absorption peak in the spectrum. Thus, this structure can be used to realize a terahertz modulator or absorption device with two outstanding functions. Using phase changes, we have also studied the slow light effect, and we find that there is a broad ultrahigh-group-index band, and the maximum group index can reach 216. This research may open up new avenues for slow light devices.

Abstract-Theoretical Analysis of Plasmon-Induced Transparency in Ring-resonators Coupled Channel Drop Filter Systems

• Shiping Zhan, 
• Hongjian Li, 
• Guangtao Cao, 
• Zhihui He, 
• Boxun Li, 
• Hui Xu

http://link.springer.com/article/10.1007/s11468-014-9760-x

The plasmon-induced transparency (PIT) in ring-resonators coupled channel drop filter (CDF) systems is investigated theoretically and numerically in this paper. A coupled mode theory-based transfer matrix method (CMT-TMM) is introduced owning to the symmetric and evanescent coupling, which is confirmed by the finite-difference time-domain (FDTD) simulation results. The drop waveguide provides the necessary optical feedback for the interference effect in realizing the PIT, and a new way for adjusting PIT effect in a fixed structure is also given. Finally, the phase and the group dispersion in the transparency window are discussed for investigating the slow light effect in our systems, and a group index of ~22 is obtained. The proposed plasmonic systems possess both the slow light and the dropping properties and may have potential and flexible applications in fundamental research of integrated plasmonic devices.