Fig. 4: Highly efficient soliton microcombs and microwave frequency synthesis.
From: Surpassing the nonlinear conversion efficiency of soliton microcombs
a, A simplified diagram of the measurement set-up, including a picture of the optically coupled chip with power supplied to heater pads through positional probes. A high-speed photodiode transforms the output pulses into a microwave tone at a frequency equal to the repetition rate. b, The measured spectrum of a microcomb operated with 35% conversion efficiency. The inset shows the repetition-rate beat note at 49.85 GHz measured in an ESA. c, The power spectral density (PSD) of the repetition-rate beat note measured using a phase noise analyser (PNA).
