Fig. 1. Schematic diagram of (a) cascade SRS and (b) cascade FWM.

Fig. 2. Schematic diagram of the experimental setup.

Fig. 3. Spectra of the generated Raman frequency comb under the 532 nm pump for SF6 gas.

Fig. 4. Pulse shapes of the S0, AS1 (normalized), S1 (normalized), and S4 (normalized) laser beams.

Fig. 5. S1 photon conversion efficiencies under different pump energies and pressures of SF6.

Fig. 6. Photon conversion efficiencies of S1, S2, S3, and AS1 versus the pump energies at 1.5 MPa SF6.

Fig. 7. S1 conversion efficiencies versus the pump energies under 1.5 MPa H2 and SF6.

Fig. 8. S1 conversion efficiencies versus the pump energies of 1.5 MPa SF6 with He carrier gas under a repetition rate of 10 Hz. The pressures of He were 0 MPa, 0.5 MPa, 1.0 MPa, and 1.5 MPa, respectively. The vertical lines represent the error bars.