Surface plasmon-induced transparency in a cut wire-coupled graphene split ring resonator

In this paper, a cut wire (CW)-coupled, orthogonally distributed graphene split ring (GSR) resonator is proposed to realize the optical analogy of electromagnetically induced transparency (EIT) in the mid-infrared regime. The dipolar surface-induced bright mode resonance of the GSR interferes constructively or destructively with the dark modes, which develops a rather pronounced transparency window in the absorption profile. This transparency is mainly attributed to the superposition of the interference effect, thus providing an alternative way of mimicking EIT in the classical optical field. The polarization of the incident beam and the position where the CW is located play significant roles in resonance modulation. The resonant wavelength and the bandwidth of the transparency window can be tuned by changing the geometrical parameters or the optical properties of graphene. The proposed device is sensitive to the substrate index and the corresponding resonant wavelength shift can be applied to detect this change; furthermore, ultra slow light with group index of over 992 is realised within the transparency window. These results may find potential use in optical sensors and switches.