Nature - USA (2020-05-14)

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Extended Data Fig. 5 | Pump frequency sweep linearization via the delayed
homodyne method. a, Setup for pump-laser frequency measurement via
delayed homodyne detection and chirp linearization feedback. Calibration of
the MZI is performed by fitting the frequency-dependent phase modulation
response of the MZI. b, Initial frequency modulation, when the VCO is driven
with a triangular ramp, determined using a Hilbert transform. The measured
frequency is compared with the targeted ideal modulation. The ramp

frequency is 100 kHz. The red-shaded regions around the extremal points are

excluded from the linearization update. c, Final triangular frequency

modulation pattern, after 20 iterations. Convergence achieved after four

iterations. d, Evolution of the root-mean-square frequency deviation during

the optimization loop. e, Evolution of the deviation between measurement and

target sweep, at each iteration of the loop.