Gain-driven Synchronization and Asymmetric Bound States in the Continuum Within Non-Hermitian Circuit Model

The gain-driven emission in gain–loss coupling systems attains significant interest. In this work, we study the monochromatic oscillation of a gain–loss coupling system through a circuit model, where the monochromacy is manifested as the gain-driven synchronization of two coupled oscillators. The synchronized oscillation in this model is theoretically studied and experimentally manifested. Benefiting from the conceptual simplicity of a circuit model, a pair of asymmetric long-living states is found among the unstable gain-driven monochromatic oscillations, corresponding to bound states in the continuum of coupling physics.