Dissipative Kerr Solitons in an Active Microcavity

ABSTRACT The advancement of soliton microcombs has significantly impacted information science, yet their generation in passive microcavities poses limitations due to the need of a high intrinsic quality ( Q) factor. Conversely, creating laser solitons in active microresonators is hindered by restricted doping volume, gain bandwidth, and opto‐thermal effects. Here, we demonstrate precise and large‐scale optical control over intracavity loss factor ( κ in ) and coupling loss factor ( κ ex ) in active microcavities by embedding erbium ions (Er 3+ ) on the cavity surface. This approach enables low‐threshold operation, broad comb spans, and enhanced intracavity power without needing external pumping‐amplification for the generation of dissipative Kerr solitons. It offers noise‐suppressed characteristics from amplified spontaneous emission while facilitating dynamic soliton manipulation, allowing deterministic single‐soliton generation even in low‐ Q microcavities. Our findings introduce a paradigm for active microcavity solitons (AMCSs) that merge the benefits of coherent and incoherent pumping in compact photonic systems, paving a way for versatile microcomb‐based photonic applications.