Fig. 3: Microcomb stabilization.
From: Vernier microcombs for integrated optical atomic clocks
a–f, Electrical spectrum analyser traces of the three beats for stabilization: fLO-FC (a and b), fxCEO/8 (c and d) and fVernier/8 (e and f) when they are unlocked (blue traces) and phase-locked (orange traces). These traces are measured at the lockbox monitor outputs, and the beats are divided by an additional factor of 2. The resolution bandwidth is 3 kHz, and the spectral span is 2 MHz. g, The fractional Allan deviation of the repetition rates of the main (orange) and the Vernier (yellow) combs, the pump laser (purple) and the FC reference’s repetition rate (and, hence, an estimate of its fractional optical stability) (blue).
