PT-Symmetric Cladding Layers for high-Q Brewster Modes and Embedded Eigenstates

Epsilon near-zero (ENZ) materials have been raising significant interest in various research areas. Rich concepts such as photonic doping and supercoupling featuring ENZ materials have been reported. ENZ materials have been proven to be instrumental to achieve embedded eigenstates, or self-sustained electromagnetic resonances in open structures with momentum compatible with the radiation continuum. However, unavoidable absorption in realistic ENZ materials results in a finite lifetime of these modes, and decay to radiation. Here, we present a strategy to tackle the losses of ENZ materials in order to produce unbounded high-Q resonances with the use of PT-symmetry and the concept of suppressed leakage. These results pave the way to efficient light trapping and sensing applications with realistic ENZ materials.