2021/02/13 by Zarko Sakotic, Alex Krasnok, Sakotic, Zarko +5 · 1 citation
Materials Science · Engineering · Physics and Astronomy · #Metamaterials and Metasurfaces Applications #Advanced Antenna and Metasurface Technologies #Quantum Mechanics and Non-Hermitian Physics
paper · pdf · doi:10.48550/arxiv.2102.06958
Epsilon-near-zero and epsilon near-pole materials enable reflective systems\nsupporting a class of symmetry-protected and accidental embedded eigenstates\n(EE) characterized by a diverging phase-resonance. Here we show that pairs of\ntopologically protected scattering singularities necessarily emerge from EEs\nwhen a non-Hermitian parameter is introduced, lifting the degeneracy between\noppositely charged singularities. The underlying topological charges are\ncharacterized by an integer winding number and appear as phase vortices of the\ncomplex reflection coefficient. By creating and annihilating them, we show that\nthese singularities obey charge conservation, and provide versatile control of\namplitude, phase and polarization in reflection, with potential applications\nfor polarization control and sensing.\n