Observation of electromagnetically induced transparency-like transmission in terahertz asymmetric waveguide-cavities systems.

Electromagnetically induced transparency (EIT)-like transmission was demonstrated in terahertz asymmetric parallel plate waveguides with two identical cavities. By shifting the position of the bottom cavity from the symmetric position in the propagation direction, both the phases of the propagating wave at resonances and the coupling strengths between two cavities are changed, resulting in exciting the additional asymmetric resonance and manipulating the detuning of two different resonant frequencies. The transparent peak between two resonances comes from the cancelation of symmetric and asymmetric resonances. We also use the physical picture of excitation of quasi-dark mode to explain this EIT-like transmission, which is similar to the metamaterial systems.