Stimulated Raman scattering in natural crystals of fluorapatite, Ca5(PO4)3F

Hexagonal Ca-5(PO4)(3)F, known as natural crystal fluorapatite and oldest host-crystal for Ln(3+)-lasant ions, is presented as a Raman-active material. High-order Raman-induced.(3)-nonlinear processes are discovered in natural crystals of fluorapatite under picosecond pumping at 1.064 mu m and 0.532 mu m wavelength. A multitude of Stokes and anti-Stokes components is generated in the ultraviolet, visible and near-infrared spectral region by stimulated Raman scattering (SRS) and Raman four-wave mixing (FWHM), resulting in a frequency comb with a width of 520 THz. The spectral lines are identified and attributed to the nu(1)(A(g)) vibration mode of the tetrahedral [PO4] units which is related to a Raman shift of omega(SRS) approximate to 965 cm(-1). The first Stokes steady-state Raman gain coefficient in the near-infrared spectral range is estimated to be > 0.38 cm.GW(-1). Finally, a short review of SRS-promoting vibration modes and observed.(3)-nonlinear interactions in all known SRS-active natural crystals (minerals) is given.