Tetragonal LiLuF 4 – A novel crystal simultaneously active for SRS‐ and Ln 3+ ‐lasing

In this paper, the first investigation of stimulated Raman scattering (SRS) effects in the tetragonal crystal LiLuF 4 is presented. It is known as a promising host‐material for trivalent lasant lanthanides (Ln 3+ ). We discovered its three “original” and one “combined” SRS‐promoting modes at room temperature under picosecond laser excitation in the visible and near‐IR spectral range. Apart from multi‐phonon Stokes and anti‐Stokes generation, we observed cross‐cascaded χ (3)  ↔ χ (3) processes involving different pairs of SRS‐active phonons. Furthermore, a comparative estimation of the stead‐state Raman gain coefficient for first Stokes generation in LiLuF 4 related to the most active SRS‐phonon mode with ω SRS1  ≈ 323 cm −1 has been carried out for both the visible and near‐IR. A brief review of the pioneering publications on laser action in Ln 3+ ‐ions of all known fluoride SRS‐active single crystals is given in tabular form as well.