Fig. 4: Phase-noise reduction and optomechanical frequency division.

a Measured one-sided phase noise spectral density for the free-running (black), injection-locked (colored), and RF injection signal (gray). The RF power used for the injections was −7 dBm (ε ≈ 5.5%); b Phase noise spectral density evolution as a function of the RF power for the 4:1 injection; c Comparison between experimental data sidebands and the semi-analytical model prediction (see Supplementary Note 7). The colormap is the experimental power spectral density (PSD) around the OMO fundamental frequency. The RF drive frequency was set to the OMO frequency for all the RF powers shown. The black dashed lines are the experimental fit and the red/blue curves are the semi-analytical prediction, showing excellent agreement; d Experimental PSD, in gray, for a RF power of −13 dBm (ε ≈ 2.75%), which is the same horizontal dashed gray linecut at (c) showing the agreement between semi-analytical model and experimental data for these sidebands, for both frequency and linewidth; e Schematic of the optomechanical frequency divider; LPF means “low-pass filter”; f Experimental Optomechanical frequency division. The orange, blue and red curves are the injection-locked signal output from the OMO for the cases 2:1, 3:1, and 4:1, respectively. The overlapping black curves are the divided signal obtained using a low-pass filter with 48 MHz cutoff frequency.