An analysis of hollow-core fiber for applications in coherent femtosecond spectroscopies

We report on the performance of Ar-filled hollow-core fibers (HCFs) capillary driven by long pulses ( > 100 fs) of moderate energy ( < 600 μ J) for coherent multidimensional spectroscopy in the visible range. The source is characterized by high overall transmission and excellent spatial mode. Broadening is achieved by self-phase modulation. Notably, the uncompressed visible output is shorter than the input pulse. This peculiar observation is explained by the structure of self-phase modulated pulses, coupled with spectral filtering. By virtue of its simplicity, low requirements, spectral stability, and the excellent properties of its spatial output, HCFs can provide an interesting alternative to achieve broadband visible pulses for broadband optical excitation and multidimensional spectroscopy applications.