Stimulated Raman Scattering in Alkali-Earth Tungstate and Molybdate Crystals at Both Stretching and Bending Raman Modes under Synchronous Picosecond Pumping with Multiple Pulse Shortening Down to 1 ps

• Main Authors: Milan Frank, Sergei N. Smetanin, Michal Jelínek, David Vyhlídal, Vladislav E. Shukshin, Lyudmila I. Ivleva, Elizaveta E. Dunaeva, Irina S. Voronina, Petr G. Zverev, Václav Kubeček
• Format: Article
• Language: English
• Published: MDPI AG 2019-03-01
• Series: Crystals
• Subjects: alkali-earth tungstate; molybdate crystals; stretching; bending Raman modes; stimulated Raman scattering
• Online Access: https://www.mdpi.com/2073-4352/9/3/167

Comparative investigation of characteristics of spontaneous and stimulated Raman scattering (SRS) in different alkali-earth tungstate and molybdate crystals at both high and low frequency anionic group vibrations is presented. It has been found that, among these crystals, the SrMoO₄ and SrWO₄ crystals are the most perspective for SRS generation on both stretching and bending modes of internal anionic group vibrations with the strongest SRS pulse shortening under synchronous laser pumping because of not only highly intense stretching mode Raman line for efficient primary extra cavity long-shifted SRS conversion but also the widest bending mode Raman line for the strongest SRS pulse shortening down to the inverse width of the widest Raman line (~1 ps) at secondary intracavity short-shifted SRS conversion. The strongest 26-fold pump pulse shortening down to 1.4 ps at the Stokes component with the combined Raman shift in the synchronously pumped extra cavity SrMoO₄ and SrWO₄ Raman lasers has been demonstrated. It was found that synchronously pumped cascade SRS with combined Raman shift is more efficient in the SrWO₄ crystal because the bending mode Raman line is more intense relative to the stretching mode Raman line than that in SrMoO₄.