Abstract
Investigation of the spectral response of graphene-dielectric (SiO2)-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 MgF2 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.
Highlights
The propagation of electromagnetic waves through periodic structures have been of great importance as these exhibit photonic band-gaps where photons of particular frequencies cannot propagate – the feature that can be harnessed for multifarious technological applications, such as designing optical sensors, narrow-band optical sources, optical filters, one-dimensional (1D) photonic crystals, etc. [1]–[8]
Similar to what observed before in fig. 6, we find that the increase in μc results in larger width of the stop-band, and the position of defect mode moves toward higher frequencies
The study essentially yields that the defect mode and its characteristics can be tuned by changing the incidence obliquity, which adds more tunability property to the proposed structure, apart from the use of chemical potential of bilayer graphene (BLG) used in the design
Summary
The propagation of electromagnetic waves through periodic structures have been of great importance as these exhibit photonic band-gaps where photons of particular frequencies cannot propagate – the feature that can be harnessed for multifarious technological applications, such as designing optical sensors, narrow-band optical sources, optical filters, one-dimensional (1D) photonic crystals, etc. [1]–[8]. The investigation of spectral characteristics of such periodic mediums remains important, that essentially includes the studies of transmission, reflection and absorption properties. These periodic structures have been studied incorporating varieties of mediums as the properties of those can be exploited, along with the operating conditions, to exhibit. Varieties of graphene-based THz absorbers have been reported in the literature [48]–[50] In this communication, we investigate certain graphene-embedded periodic structures in respect of the transmission properties. The structure inherits the applications of such materials, as [56], [57] determine
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