Achieving a High Q-Factor and Tunable Slow-Light via Classical Electromagnetically Induced Transparency (Cl-EIT) in Metamaterials

Plasmonics - We report on our numerical work concerning a 3D planar nano-structure metamaterial exhibiting classical electromagnetically induced transparency (Cl-EIT). The interaction between two...     

Disappearance of Plasmonically Induced Reflectance by Breaking Symmetry in Metamaterials

Although, using cut-out I-II and H-II structures, it has been proved that symmetry broken is necessitous to have a plasmonically induced reflectance (PIR) but it is also possible to create PIR effect in a symmetric cut-out H-II structure. In this paper, in addition to reaffirming the possibility of creating PIR effect in symmetric structure using I-II structure, it is also proved, for both the I-II and H-II structures, that the created PIR effect in symmetric case can be vanished by breaking the symmetry. The created PIR effect in the two I-II and H-II structures will be compared in different situations.     

Tunable Slow Light in Graphene Metamaterial in a Broad Terahertz Range

A graphene-based metamaterial with tunable electromagnetically induced transparency is numerically studied in this paper. The proposed structure consists of a graphene layer composed of H shape between two cut wires, by breaking symmetry can control EIT-like effects and by increasing the asymmetry in the structure has strong coupling between elements. It is important that the peak frequency of transmission window can be dynamically controlled over a broad frequency range by varying the chemical potential of graphene layer. The results show that high refractive index sensitivity and figure of merit can be achieved in asymmetrical structures which is good for sensing applications. We calculated the group delay and the results show we can control the group velocity by varying the S parameter in asymmetrical structure. The characteristics of our system indicate important potential applications in integrated optical circuits such as optical storage, ultrafast plasmonic switches, high performance filters, and slow-light devices.     

Subwavelength Micro-Antenna for Achieving Slow Light at Microwave Wavelengths via Electromagnetically Induced Transparency in 2D Metamaterials

In this paper, a tunable slow light 2D metamaterial is presented and investigated. The metamaterial unit cell is composed of three metallic strips as radiative and non-radiative modes. Once introducing asymmetry, a transparency window induced by coupling between the dark and bright modes is observed. The transmission characteristics and the slow light properties of the metamaterial are verified by numerical simulation, which is in a good agreement with theoretical predictions. The impact of asymmetric parameter on transparency window is also investigated. Simulation results show the spectral properties and the group index of the proposed 2D metamaterial can be tunned by adjusting asymmetric structure parameter, temperature and also the metal used in the metamaterial. Furthermore, the electromagnetic field distributions, excited surface currents, induced electric dipole and quadruples, and slow light properties of the metamaterial are investigated in details as well as transmission spectral responses. The outstanding result is that, the 2D-metamaterial is in a high decrease of the group velocity and therefore slow light applications, because in the best state, the group velocity in our structure decreases by a factor of 221 at T=100 K using copper as metal in optimization asymmetric case.     

New Approach of Plasmonically Induced Reflectance in a Planar Metamaterial for Plasmonic Sensing Applications

We theoretically demonstrate and investigate plasmonically induced reflectance (PIR) in a new planar metamaterial with two completely different approaches. Here, we not only show that broken symmetry is a general strategy to create electromagnetically induced reflectance (EIR)-like effect but also demonstrate that the nanoplasmonic EIR can be realized even without broken symmetry via the excitation of the higher-order plasmonic modes in the same designed planar metamaterial. In nanophotonics, plasmonic structures enable large field strengths within small mode volumes. Therefore, combining EIR with nanoplasmonics would open up the way toward ultracompact sensors with extremely high sensitivity. In the second approach of creating the PIR of our proposed nanostructure, the restrictions on size are partially relaxed, making fabrication much easier. Their interactions and coupling between plasmonic modes are investigated in detail by analyzing field distributions and spectral responses. Also, we show that the PIR frequency position depended very sensitively on the dielectric surrounding. Furthermore, the narrow and fully modulated PIR features due to the extraordinary reduction of damping may serve for designing novel devices in the field of chemical and biomedical sensing.