Fig. 1. Schematic of field propagation direction and detection area of a Gaussian beam incident on a single nanoparticle from above down

Fig. 2. Typical example of SMS technique. (a) Schematic setup for SMS technique^[33]; signal components of (b) $f$ and (c) $\mathrm{2}f$ of particles at different $\left(x,y\right)$ relative to beam measured by SMS technique^[19]

Fig. 3. Comparison of schematic setups for T-SMS and R-SMS. (a) T-SMS technique^[33]; (b) R-SMS technique^[34]

Fig. 4. Schematic of experimental setup for modulating beam position^[37]. Beam modulation is realized by changing angle at back focal plane by using a Glavo mirror; inset shows that modulation can also be achieved by an acousto-optic deflector (AOD)

Fig. 5. Experimental schematic of modulating polarization^[44]. (a) Experimental setup of rotating linear polarization of laser at ${\omega }_{\mathrm{0}}$ and temporal modulation through a chopper at ${\omega }_{\mathrm{2}}$; (b) spectrum of output signal where interested $\mathrm{4}f$ frequency (angular frequency $\mathrm{4}{\omega }_{\mathrm{0}}$) component is separated from interfering ones; (c) geometric diagram of a nanoantenna to be measured; (d) scanning electron micrograph (TEM) image of a nanoantenna

Fig. 6. Schematic of ultrafast time-resolved pump-probe spectroscopy for sample nonlinearity measurement^[48]

Fig. 7. Schematic of FT-SMS setup^[62]

Fig. 8. Experimental setup for separation of scattering and absorption cross section spectra using a common-path interferometer^[63]

Fig. 9. SMS technique combined with incoherent imaging system^[36]. (a) Schematic of SMS technology combined with incoherent imaging; (b), (c) comparison of stability effects of extinction cross section with and without defocus feedback

Fig. 10. Relationship between size of nanostructure and its spectrum^［79］.（a）Diagram of environment-controlled $\mathrm{A}\mathrm{g}@\mathrm{S}\mathrm{i}{\mathrm{O}}_{\mathrm{2}}$ particle；（b）extinction cross section spectrum of particle measured by SMS technique；（c）linear dependence of extinction cross section spectrum $\Gamma$ of small size single Ag@SiO₂ particle on inverse of $D_{\mathrm{e}\mathrm{q}}$

Fig. 11. Comparison of polarized light spectra in different directions for asymmetric particles. (a) Absorption cross section spectra (approximately equal to extinction) of a single elliptic gold nanoparticle^[82]; (b) extinction cross section spectra of a single gold nanorod^[81]

Fig. 12. Spectra comparison of bare nanorods and silicon-coated nanorods in different environments^[93]

Fig. 13. Relationship between extinction cross section spectrum $c_{\mathrm{e}\mathrm{x}\mathrm{t}}$ and $d$ of a pair of gold spheres (R=50 nm, light polarization along dimer axis, and refractive index of surrounding medium is 1.15) ^[105]

Table 1. Major modulation schemes of SMS technique