Finally, we investigated dark-field microscopy-correlated single-particle Fano-SERS from nano-Fanowman particles under ultralow-power laser excitation (Figure ). A distinct Fano dip was observed in the dark-field scattering spectrum (Figure , left). Using a circularly polarised laser, we conducted measurements at two different excitation powers. At a laser power of 22 nW (34 nW/μm 2 , assuming a Gaussian beam with a beam waist of w = 457 nm), strong Fano-SERS signals were readily detected. Remarkably, even at an ultralow laser power of 1.2 nW (1.8 nW/μm 2 ), Fano-SERS signals remained detectable. In a single dark-field image containing 102 nano-Fanowman particles (Figure ), ~86% exhibited measurable Fano-SERS signals at 22 nW (Figure ). Importantly, the EF distribution obtained with the 22-nW circularly polarised excitation was notably narrower than that obtained previously with 500 nW linearly polarised excitation (Figure ). At the ultralow excitation power of 1.2 nW, ~16% of the same 102 particles yielded detectable Fano-SERS signals. Representative singleparticle Raman spectra acquired at these levels are presented in Figure . It should be noted that the observed Fano-SERS intensities were lower than their maximum possible values, as signals were inherently averaged over all polarisation directions due to the circularly polarised excitation. Nevertheless, the observation of a detectable SERS signal at a 1.2-nW laser power represents a significant advancement compared to the tens to hundreds of microwatts typically employed in single-nanoparticle SERS measurements. These results clearly demonstrate that incorporating Fano resonance into SERS-active nanoparticles enables SERS signal detection at extremely low laser powers. Such low-power SERS measurements have the potential to significantly improve noise-free detection, minimise laser-induced sample damage, and ultimately reduce the overall cost of SERS-based analytical applications.