Edge states in non-Hermitian photonic Chern insulators: remote excitation with a real-frequency point source.

The non-Hermitian skin effect (NHSE) provides a powerful approach for controlling wave localization beyond Hermitian systems. However, whether skin-localized modes in non-PT-symmetric photonic systems can be remotely excited by a single real-frequency source remains unclear. Here, we investigate this problem in a non-Hermitian photonic Chern insulator composed of gyromagnetic rods with dielectric gain and loss. By decomposing the non-Hermitian component into PT-symmetric and PT-symmetry-breaking parts characterized by α and β, we establish the relationship between eigenmodes and real-frequency excited fields through the imaginary part of the Bloch wave vector. We find that remote excitation is mainly determined by the ratio β/α. For the 18a×18a structure studied here, more than 80% of the field intensity can be localized within the rightmost column of unit cells when β/α<0.2. Our results provide insights into wave excitation in non-PT-symmetric systems and guide the design of non-Hermitian photonic devices.