Metamaterial inspired multifunctional structures for terahertz applications

Abstract

The scarcity of natural materials showing their characteristic signatures in terahertz frequency region has resulted in creation of a technological gap. Here, the artificially crafted micron sized subwavelength lattices popularly known as metamaterials are investigated to construct multifaceted applications in terahertz frequency domain. This is being demonstrated with an amalgamated support of numerical simulations, experimental techniques and analytical procedures. Along with this, the potential opportunities facilitated as a consequence of the interaction of metamaterials with terahertz radiations are discussed in relevance to their historical perspectives. As one of the research objectives, the concentric unit cells of asymmetric single layered metallic metamaterials are fabricated to study the role of polarization in deciding their resonant excitations at terahertz frequency. Also, the patterns of surface currents are monitored to understand the nature of resonance modes, which can pave the way to realize frequency agile photonic devices. In addition, planar geometries of graphene-based terahertz metamaterials are explored to modulate the near field electromagnetic coupling at the level of unit cell. This examination is extended further to show the dynamic tuning of slow light characteristics including group delay, group index, group velocity along with delay bandwidth product as a function of Fermi energy of graphene. Such efforts can be helpful to actualize delay lines and sensors. Moving ahead, the realm of near field strongly and weakly coupled active metamaterials is probed to control the switching of terahertz broadband resonances at relatively lower optical pump powers within range of 0-20 mW. This can inspire us to design reconfigurable functionalities in terms of modulators and switches. Finally, the emerging fascinating possibilities are addressed based on the conducted research works. newline