Bound States in the Continuum and Non-Hermitian Engineering of Hybrid TE-TM Resonances in Periodic Metasurfaces

We show that hybrid TE-TM collective resonances in periodic metasurfaces can form perfect bound states in the continuum (BICs) despite being strongly coupled to lossy meta-atoms. Furthermore, the non-Hermitian character of the studied system can be used to realize exceptional points and robust degeneracies of the hybrid bright and dark eigenstates.