Phase Noise of Kerr Soliton Dual Microcombs

Dissipative Kerr soliton microcombs are believed to be a promising technique to build dual-comb source for applications including precision laser metrology and high-speed optical signal processing. In this Letter, we conduct detailed experimental investigation on the phase coherence between two on-chip Kerr soliton microcombs. Moreover, the technique of 2-point locking and optical frequency division are explored to enhance the dual- microcomb phase coherence, and we demonstrate the best phase noise down to -50 dBc/Hz at 1 Hz offset, -90 dBc/Hz at 1kHz offset, and -120 dBc/Hz at 1 MHz offset. Our study provides a basic reference for both fundamental studies and practical applications of Kerr soliton dual microcombs that entail high mutual phase coherence.