Fig. 4: EO coupling dynamics and dispersion mapping.

a EO comb spectra measured at on-chip microwave powers of 18, 23, and 29 dBm (1550 nm pump). b Reflection spectra of the resonance mode used for optical pumping, showing increasing mode splitting with microwave power. c Extracted EO coupling strength \(g\) as a function of on-chip microwave power, exhibiting square-root dependence (solid red line). d, e EO comb spectra as a function of microwave frequency detuning \(\Delta {f}_{m}\), measured at pump wavelengths of 1530 nm (normal dispersion) and 1550 nm (near the zero-dispersion point), respectively. f, g Integrated dispersion extracted from EO comb spectra in (d) and (e), plotted relative to the microwave frequency grid defined by \({f}_{m}\). The white region denotes the range \(\left|{D}_{\mathrm{int}}\right| < g\), consistent with the measured coupling strength \(g/2\pi\) ≈ 1.49 GHz from (b).