In contrast to spontaneous Raman scattering, coherent Raman scattering techniques, such as femtosecond stimulated Raman scattering (FSRS), show advantages for many applications. Besides an enhanced signal strength, FSRS is free of a nonresonant background but is affected by cross-phase modulation (XPM). The resulting artifacts in FSRS become relevant for high pulse intensities (GW/cm2-regime) and ultrashort pulses (<2 ps), both necessary for super-resolution experiments. As the pulse duration is a crucial parameter for XPM as well as for FSRS, we present a setup in which we adjust the pulse duration across the relevant range (0.5–3 ps), in order to investigate the XPM influence on the spectra. Furthermore, we vary the peak intensity, the temporal overlap between the interacting pulses, and the nonlinear refractive index coefficient n2 of the sample, showing that a trade-off between all these quantities enables the measurement of unaffected FSRS spectra.
- cross-phase modulation
- femtosecond stimulated raman scattering
- spectral distortion