Fig. 1. Impulsive stimulated Raman scattering. (a) Schematic of ISRS; (b) relationship between spectral range of laser pulse and frequency of certain vibrational mode

Fig. 2. Setup of FT-CARS system^[25]

Fig. 3. Time-domain picture of FT-CARS process. Above the time axis is the vibrational wave packets χ(t) and χ(t+τ) excited by pulse-pair sequence, which contain various vibrational modes. Below the time axis is the vibration of the target mode with single frequency to be detected

Fig. 4. Sagnac-enhanced impulsive stimulated Raman scattering^[28]. (a) Schematic of SE-ISRS optical path; (b) comparison of Raman spectra of bromoform acquired by ISRS, FT-CARS, and SE-ISRS spectroscopies

Fig. 5. Single-pulse impulsive stimulated Raman scattering^[23]. (a) Setup of pulse shaping in single-pulse ISRS; (b) single-pulse CARS images of a glass capillary plate with CH₂Br₂. 1 is image with shaped pulse maximizing the resonant contribution of the CH₂Br₂ 577 cm^-1 level, 2 is image with shaped pulse minimizing the same mode, 3 is obtained by subtraction of image 1 and image 2, 4 is image obtained with Fourier transform-limited pulse

Fig. 6. CBZ DH crystal measured by the Raman-induced spectral shift technique^[40]. (a) Measured modulated intensity as a function of the pump-probe delay; (b) Fourier transform of the time-domain oscillations resolves the vibrational frequencies of the molecules (blue) that can be compared with the spontaneous Raman spectrum from the same sample (red); (c) image resolved around 109 cm^-1; (d) transmission image of the crystal

Fig. 7. FT-CARS imaging^[43]. (a) High-spectral imaging results of polymer beads. Top left and top right are images at 810 cm^-1 and 1003 cm^-1, below of them is the corresponding spectra; (b) high-spectral imaging results of Haematococcus lacustris cells. Top left and top right are images at 1155 cm^-1 and 800 cm^-1, below of them is the corresponding spectra

Fig. 8. THz-CARS imaging of HA and collagen (C), scale bars is 20 μm. (a) Wide-field imaging (WFI) of the ROI; (b) the ROI; (c) raw measured THz CARS spectra of the bone at two different pixels in the ROI; (d) corresponding resolved Raman spectra of HA and C; (e) HA at 239 cm^-1; (f) collagen at 56 cm^-1; (g) FWM image; (h) SHG image at 400 nm

Fig. 9. Dual-comb FT-CARS hyperspectral imaging of a capillary plate with holes filled with a mixture of hexafluorobenzene, nitrobenzene, nitromethane, and toluene