Influence of laser-induced breakdown on spectral properties, conversion efficiency, and beam quality of stimulated Raman scattering

Stimulated Raman scattering (SRS) of carbon disulfide (CS₂) was investigated under conditions with single- and dual-lens configurations. The results demonstrated that the single-lens configuration significantly enhanced four-wave mixing processes and generated more abundant anti-Stokes SRS. The differences in spectral excitation features arose from variations in the pump laser's wavevector, which resulted from differing focusing configurations. Both configurations showed the cutoff in spectral evolution. The transmittance of the pump light is strongly correlated with the SRS energy, which is attributed to the effect of laser-induced breakdown (LIB). The pulse timing diagrams show the attenuation of the pump light under the influence of LIB, as well as the cutoff of the subsequent laser. The beam quality reveals that the occurrence of LIB scatters the SRS light, which manifests as a sharp degradation of the beam quality. Temperature-dependence experiments further demonstrate the modulation of LIB on SRS at higher temperatures. These findings indicate that LIB not only suppresses spectral evolution and degrades the beam quality but also significantly modulates the SRS conversion efficiency. This work offers insights into optimizing pump light parameters and focusing configurations to increase SRS efficiency and improve beam quality and provides valuable references for the design of Raman lasers.