Wideband THz Filtering by Graphene-Over-Dielectric Periodic Structures With and Without MgF2 Defect Layer
Journal: IEEE Access (click here for full paper)
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Investigation of the spectral response of graphene-dielectric (SiO 2 )-based periodic structure was made in the far-infrared (IR) to the mid-IR frequency range, and the effects of different parametric and operational conditions on the transmission characteristics were explored. The presence of stop-bands, followed by Bragg reflection harmonics, in the low-frequency regime was observed exploiting the bilayer graphene (BLG) sheets. The width of stop-bands could be tuned by altering the number of periods as well as the chemical potential of BLG. The formation of a stop-band (with a transmission dip positioned at ~16 THz) having a span of ~3 THz was noticed, which is possibly a very large stop-bandwidth reported so far. The structure was also analyzed upon introducing a defect layer of MgF 2 having a thickness smaller than the dielectric medium. This results in shifting the position of stop-bands of the structure. The characteristics of transmission spectra were found to be greatly depending on the chemical potential (of BLG) and other operating conditions – the feature that triggers the usefulness of the proposed structure in the design of optical modulators, tunable narrow-band filters, broad-band reflectors and biosensing applications.