Graphene based metasurface with near unity broadband absorption in the terahertz gap

Abstract

This paper reports a novel graphene metasurface exhibiting near-unity absorption over a wide bandwidth of 9.74 THz ranging from 2.06 to 11.80 THz with a fractional bandwidth of 140.86% with respect to the center frequency of 6.93 THz within the terahertz gap of the electromagnetic spectrum. The proposed structure consists of two layers of graphene separated by silicon dioxide (SiO 2). On the top of SiO 2 , a modified fractal-shaped 1 nm thick graphene pattern is deposited while a square-shaped graphene pattern of identical thickness completely covers the backside of the SiO 2 substrate. The absorber was found to be polarization independent under the normal incidence of the approaching electromagnetic wave (EM) toward the top layer of the structure due to its 4-fold structural symmetry. The designed structure offers stable absorption up to 60 incident angle under TE polarization and 40 incident angle under TM polarization. The structure is~λ/55.9 thin and maintains periodicity of~λ/21.7; thereby validating the effective homogeneity condition in the sub-wavelength domain. This graphene-based absorber can find several applications including, sensors, detectors, spatial light modulators, and in spectroscopic detectors, and so forth, in the "Terahertz Gap" for next-generation 5G communication system and beyond.

Metamaterial‐based refractive index sensor using Ge2Sb2Te5 substrate for glucose detection

“…14 Ghosh et al presented a near-unity graphene metamaterial-based absorber in THz-gap with nearperfect absorption in 9.74 THz bandwidth with possible applications in next-gen 5G communication devices. 15 Sharma and coauthors presented magnetically tunable metasurface consisting of InSb-patched, InAs-patched, and unpatched pixels with an average tuning rate of 0.3 THz T −1 . 16 We presented a sensor to detect glucose levels in human blood so that the severity of diabetic patients can be determined.…”

“…Abdulkarim et al reported a square‐shaped water metamaterial‐based perfect solar absorber in a microwave regime with ultra‐broadband absorption response and with possible applications in the energy harvesting field 14 . Ghosh et al presented a near‐unity graphene metamaterial‐based absorber in THz‐gap with near‐perfect absorption in 9.74 THz bandwidth with possible applications in next‐gen 5G communication devices 15 . Sharma and coauthors presented magnetically tunable metasurface consisting of InSb‐patched, InAs‐patched, and unpatched pixels with an average tuning rate of 0.3 THz T −1 16 …”

Miniaturized dual stop band frequency selective surface with broadband linear co to cross polarization conversion ability

“…Frequency selective surface (FSS) is widely used in wireless and satellite communication as a periodic surface that can transmit or reflect the electromagnetic (EM) signal. 1 FSS founds different applications as microwave absorber, 2,3 radar cross section reduction, 4 antenna radome, 5 polarization converter, 6 sub reflector in cassegrain horn, 7 EM cloaking, 8 and as antenna superstrate for directivity enhancement. 9 Recently, circular array radiation theory is applied to represent the scattered field from a conducting cylindrical surface and the theory is extended for concentric array geometry to realize active cloaking at microwave frequency.…”

Multilayer graphene fundamental wave mixer under DC voltage bias

“…In the terahertz frequency band, graphene-based metasurface design is suitable for antennas and absorbers. [3][4][5] In theory, the properties of new graphene can evole into the properties of bulk graphite in less than 10 layers. 6 In this paper, multilayer graphene specimen was prepare from bulk graphene crystals by mechanical exfoliation method.…”