Efficient high-power 1.9 µm picosecond Raman laser in H₂-filled hollow-core fiber without generation of rotational lines

In this paper, an efficient high-power 1.9 µm picosecond Raman laser through pure vibrational stimulated Raman scattering (SRS) in H₂-filled hollow-core fiber (HCF) is demonstrated. The maximum Raman conversion efficiency of 34 % and the Raman power of 7.3 W (36.5 µJ) is achieved within a 130 cm length of our in-house fabricated fiber. By controlling the H₂ pressure, the high-order Stokes and rotational Stokes/anti-Stokes will not be generated, thereby enhancing the efficacy of the 1st Stokes conversion. In addition, the vibrational anti-Stokes are produced inevitably, which can be explained by the phase-matching of higher-order modes. Our results show SRS in H₂-filled HCF to be a promising method for generating high-power 1.9 µm picosecond pulses, which are valuable in spectroscopy, defense, and efficient nonlinear conversion.