Sculpting non-Hermitian light in the continuum

PT- or anti-PT-symmetric non-Hermitian photonic systems can exhibit responses such as phase transitions, slow light, and asymmetric modal evolution near an exceptional point (EP), but realizing a phase-transition process that satisfies anti-PT symmetry and passes through an EP on an integrated platform remains challenging. A smart research from Xiankai Sun's group at the Chinese University of Hong Kong (CUHK) recently demonstrated that two quasi-BIC modes generate dissipative coupling to the same radiative continuum, enabling anti-PT phase transitions and EPs on a silicon-based integrated photonic platform without additional lossy materials or auxiliary lossy waveguides. This provides a new physical framework for exploring the intersection of BIC photonics and non-Hermitian photonics.