Mode enhancement in asymmetric coupled non-Hermitian microcavities

Coupled microcavity systems (CMSs) are central to integrated photonics for engineering mode interactions. While PT-symmetric and supersymmetric CMSs enable single-mode lasing, their compact mode volumes impose high lasing thresholds. Here, we demonstrate an external-cavity assisted lasing scheme using two asymmetrically sized rings: the larger cavity channels pump energy to the smaller one, effectively lowering its threshold and sustaining emission. Experiments confirm this gain transfer by monitoring spectral evolution under varying pump distributions. This approach provides a practical route to enhance microcavity lasing efficiency and deepens understanding of non-Hermitian interactions in coupled resonators.