Table 1 Comparison of dual-comb based techniques for imaging of SM dynamics and laser diagnostics

	EFXC	IXC
Response	Linear	Nonlinear (two-photon)
Interferometric	Yes	No
Polarization matching required	Yes	No^§
Required average power	1–100 μW	~10 μW*–100 mW
Required pulse-width	Arbitrary	~ps^¶ or lower
Spectral overlap	Required	No, only photon energies must add
Access to molecular phase	Yes	No
Lock between the lasers	Not needed for multiplexed cavities	Not needed
Aliasing problem	Yes, bandwidth \(\Delta \nu \le {f}_{{{{{{{{\rm{r}}}}}}}}}^{2}/(2\Delta {f}_{{{{{{{{\rm{r}}}}}}}}})\)	No^†, but limited by the LUT dynamics

EFXC electric field cross-correlation, IXC intensity cross-correlation.
^§Avoiding polarization alignment between the two lasers prevents interferometric effects that would arise like in fringe-resolved IAC when operating at the same wavelength.
*Photodetectors with higher nonlinear coefficients should grant access to probing pulsed lasers with 1 μW or lower average power. Currently, it is several μW.
^¶Longer pulses (dozens of ps) should also be detectable when a higher sensitivity two-photon photodetector is used.
^†Operation high above the aliasing limit requires a careful choice of Δf_r with respect to the pulse width.

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