Research Projects

Loss in a physical system is inevitable and generally considered detrimental from its practical application perspectives. However, apparently illusive exceptional points (EPs) that can offer extraordinary physics, can be realized through judicious interplay of gain and loss in a non-Hermitian PT-symmetric quantum system. In spite of that, realizing EP in a photonic system is not straight-forward, courtesy existence of the inherent losses. However, artificially engineered metasurfaces can provide unique opportunities in simultaneously controlling loss and gain mechanisms in a photonic system with suitable design variations. Implementing thoughtful strategies in metasurface designs can establish certain path to attain EP. Motivated with this background, here, we are proposing a pair of near-field coupled dark- bright- mode resonances assisted terahertz metasurfaces mimicking a typical non-Hermitian PT symmetric system. Structurally, a pair of orthogonally twisted split ring resonators forms the bright- dark- resonance modes at the metasurface unit cell level for orthogonally polarized incident THz probe beam. Utilizing such meta system, we plan to achieve EP while operating in the THz frequency domain. Our approach will consist of theoretical as well as experimental techniques. Successful demonstration of EP will be followed by development of a metasensor to detect monolayer of graphene, establishing the extraordinary sensing capability that EP can offer in detecting ultra thin, sub-nanometer scale materials (for example, quantum materials, bio materials etc),