The Epsilon-Near-Zero (ENZ) super-tunneling structure with weakly coupled cascaded ultra-narrow channels is proposed and demonstrated to have notably wider bandwidth than single stage tunneling structure. An extensive parametric study for such structures is performed to investigate the factors which can affect super-tunneling performance. It is found that the coupling between the ultra-narrow channels is required to be weak enough to ensure a continuous supertunneling band. In addition, electric field in the cascaded channels is enhanced, compared with that in the single channel structure.
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