Combined theoretical analysis for plasmon-induced transparency in integrated graphene waveguides with direct and indirect couplings
1 School of Physics and Electronics Science, Hunan University - Changsha 410082, China
2 School of Science, Jiangnan University - Wuxi 214122, China
Received: 18 May 2015
Accepted: 29 July 2015
By taking a graphene nanoribbon as a resonator, we have numerically and analytically investigated the spectral characteristics of plasmon-induced transparency in integrated graphene waveguides. For the indirect coupling, the formation and evolution of the transparency window are determined by the excitation of the super resonances, as well as by the destructive interference and the coupling strength between the two resonators, respectively, while for the indirect coupling, the peak transmission and corresponding quality factor can be dynamically tuned by adjusting the Fermi energy of graphene nanoribbons and the transparency peak shifts periodicity with the round-trip phase accumulated in the graphene waveguide region. Analytical results based on temporal coupled mode theory (CMT) show good consistence with the numerical calculations. Our findings may support the design of ultra-compact plasmonic devices for optical modulating.
PACS: 42.82.Et – Waveguides, couplers, and arrays / 73.20.Mf – Collective excitations (including excitons, polarons, plasmons and other charge-density excitations) / 78.67.Wj – Optical properties of graphene
© EPLA, 2015