Triple plasmon-induced transparency in graphene and metal metamaterials and its anomalous property

Abstract

A silicon-graphene-silica periodic graphene metamaterial, comprising of a graphene-strip, graphene-block, and graphene-ribbon, is proposed to realize dynamic triple plasmon-induced transparency (PIT). Coupled mode theory is employed to explain this phenomenon, and the results are in close agreement with the finite-difference time-domain simulation. It is interesting to note that the triple-PIT can also be realized by using silver instead of graphene and silicon layer. When the Fermi level of the graphene is 0.75 eV, the difference of the triple-PIT based on the two structure types is easily analyzed because the resonant frequencies are effectively coincident. As a result, the structure of graphene exhibits better absorption characteristics compared with that of silver, however, it decreases with increasing Fermi levels within graphene. Thus, the higher Fermi level of graphene is not suitable for the absorbers. Furthermore, the anomalous property of graphene triple-PIT that is attributed to the interaction way of the dark mode differing from the bright mode is analyzed compared with the silver triple-PIT, and it can be used to compensate for the defects of silver PIT. This study is significant for the absorber for which the graphene is utilized. The insights gained from the comparison between metal and graphene are crucial to the design of the metamaterials for which graphene and metal are used.