Chaotic dynamics on exceptional surfaces

Due to strong photon-phonon interaction, coupled microcavities have provided a fruitful platform for chaos investigation. In particular, the parity-time symmetric microcavities pair has attracted unprecedented attention since the exceptional point (EP) in the non-Hermitian system offers more intriguing and abundant dynamics. Motivated by achieving a robust EP, a novel exceptional surface (ES) notion is proposed in the coupled microcavities. However, the chaotic dynamics on the ES remain yet unexplored. This study explores the chaos generation on the ES. We discover that the ES could dramatically decrease the threshold of chaos generation by >50% compared to the eigenvalues escaping from the ES. Unlike conventional chaotic dynamics, chaotic signals on the ES possess a surprising globally flattened, but locally chirped spectrum. Such an advantage provides an additional degree of freedom to implement chaotic applications on the physical layer. In addition, a coupling phase-induced chaos is found, which demonstrates an accumulated chaos generation beyond the conventional wisdom. More importantly, such an arrangement enables chaotic signals to achieve the temporal Vernier and harmonic Vernier effects, expanding the scope of chaos. This study of chaos generation on the ES further stimulates applications in compact chaotic devices and potentially facilitates fundamental chaotic dynamics research.