Intracavity characterization of micro-comb generation in the   single-soliton regime
  Soliton formation in on-chip micro-comb generation balances cavity dispersion and nonlinearity and allows coherent, low-noise comb operation. We study the intracavity waveform of an on-chip microcavity soliton in a silicon nitride microresonator configured with a drop port. Whereas combs measured at the through port are accompanied by a very strong pump line which accounts for >99% of the output power, our experiments reveal that inside the microcavity, most of the power is in the soliton. Time-domain measurements performed at the drop port provide information that directly reflects the intracavity field. Data confirm a train of bright, close to bandwidth-limited pulses, accompanied by a weak continuous wave (CW) background with a small phase shift relative to the comb. 
Pei-Hsun Wang, Jose A. Jaramillo-Villegas, Yi Xuan, Xiaoxiao Xue,   Chengying Bao, Daniel E. Leaird, Minghao Qi, and Andrew ...
physics.optics