Wideband tunable mid‐infrared cross‐polarisation converter using monolayered graphene‐based metasurface over a wide angle of incidence

Abstract

In this study, the authors have designed and proposed a monolayer graphene‐based metasurface, performing as a broadband polarisation converter over a wide angle of incidence. The unit cell of the metasurface consists of split ring generated over a perforated single layer of graphene grown over metal‐backed silicon dioxide. The structure converts incident linearly polarised wave into its cross‐polarised component over a wide bandwidth with peak polarisation conversion exhibits value to unity. The plane of polarisation of the incident electromagnetic wave is rotated orthogonally on reflection from the proposed metasurface over full width at half maxima bandwidth around 72.83% compared with centre frequency of 2.16 THz, which can be maintained up to 40° incident angles under both transverse electric and transverse magnetic polarisations. The proposed structure is as thin as ∼λ/7.3 with respect to lowermost frequency and the period of the structure is about λ/10.7. The frequency band of polarisation conversion can be tuned by altering chemical doping as well as the electrostatic grating of the graphene sheet. The structure can find applications toward sensing, spectroscopy etc.

Tunable Dual-Band Ultrasensitive Stereo Metamaterial Terahertz Sensor

“…At present, the application of metamaterials is very extensive, and the technology combined with microfluidics has been applied to the detection of biomolecules [2,10,15,16]. These promising sensing tasks are typically achieved by measuring the difference in the resonance response of the metamaterial [17,18,19,20]. When the analysis sample is overlaid on top of the metamaterial, the altered resonance response is converted into a significant change in the transmitted or reflected signal in the response spectrum, and these changes can be detected directly [18,21].…”

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

“…Some of the recent studies have indicated that the incorporation of lumped elements to enhance absorption bandwidth; however, they are quite challenging to realize in practice and contradict the ultra‐thin concept 9 . Recently, atomically‐thin two‐dimensional (2D) graphene‐based metasurfaces have attracted huge research attention owing to the controllability of graphene's conductivity, which helps in developing various metasurface related structures in THz frequency regions 10‐13 . In specific, graphene offers tunability in absorption bandwidth, where the conductivity of graphene has been modulated by controlling external parameters like chemical doping and mechanical straining 14‐17 .…”

A highly efficient low‐cost reflective anisotropic metasurface for linear to linearly cross‐ and circular‐polarization conversion

“…Due to low profile and broad applications in microwave and optical fields several metasurface‐based designs have been studied comprising metasurface based slotted patch antenna, 6 metantenna, 7 tuneable metasurface, 8 compact metamaterial absorber 9 . Several metasurface designs for cross‐polarization conversion in terahertz domain are proposed in References 10‐13.…”