Observation of Parametric Beat-Driven Breathing Solitons in Auxiliary-Pump-Assisted Microcombs

Optical frequency combs generated in Kerr microcavities offer a promising platform for miniaturizing comb systems. While single-pump configurations have been extensively investigated, dual- and multi-pump schemes provide new degrees of freedom for precisely controlling and tailoring the comb generation dynamics and properties. Here, we demonstrate soliton breathing phenomena induced by co-propagating pumps in the auxiliary-pump-assisted microcomb generation scheme, referred to as parametric beat-driven breathers. These breathers exhibit a unique existence range and a clear dependence on breathing frequency, significantly differing from intrinsic and intermode breather solitons. We experimentally reveal the relationship between the breathing and pump frequencies and a mode-number-dependent distribution of the relative breathing depth across comb lines. Breathing enhancement phenomena triggered by avoided mode crossings are also observed. Theoretical analysis and numerical simulations based on the dual-pump Lugiato-Lefever equation agree with experimental results. Our findings not only uncover critical instability features in co-polarized dual-pump-generated microresonator soliton frequency combs but also fundamentally highlight the necessity of pump architecture optimization for achieving enhanced stability and operational performance in practical Kerr-comb-based photonic systems.