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

Abstract

Hexagonal Ca5(PO4)3F, known as natural crystal fluorapatite and oldest host‐crystal for Ln3+‐lasant ions, is presented as a Raman‐active material. High‐order Raman‐induced χ(3)‐nonlinear processes are discovered in natural crystals of fluorapatite under picosecond pumping at 1.064 μm and 0.532 μm 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 ν1(Ag) vibration mode of the tetrahedral [PO4] units which is related to a Raman shift of ωSRS ≈ 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 χ(3)‐ nonlinear interactions in all known SRS‐active natural crystals (minerals) is given.

Novel efficient SrMgY3(SiO4)3F:Ce3+,Tb3+ phosphor with tunable color and thermal stability through energy transfer

“…The XRD spectra of all samples were extremely similar with a good fit, and no impurity phases were detected. To further explore the crystal structure of SMYSF, the Rietveld structure refinements of SMYSF and SMYSF:0.06Ce 3+ ,0.90Tb 3+ were carried out using the crystal structure data of Ca 5 (PO 4 ) 3 F as a starting model 25 …”

“…To further explore the crystal structure of SMYSF, the Rietveld structure refinements of SMYSF and SMYSF:0.06Ce 3+ ,0.90Tb 3+ were carried out using the crystal structure data of Ca 5 (PO 4 ) 3 F as a starting model. 25 F I G U R E 1 X-ray diffraction (XRD) patterns of SMYSF:0.06Ce 3+ , SMYSF:0.10Tb 3+ , SMYSF:0.06Ce 3+ ,0.06Tb 3+ , SMYSF:0.06Ce 3+ ,0.90Tb 3+ , and SMYSF:0.06Ce 3+ ,1.80Tb The observations, calculations, and differences by the XRD refinement process of SMYSF and SMYSF:0.06Ce 3+ ,0.90Tb 3+ are shown in Figure 2A,B. The main crystallographic parameters are shown in Table 1.…”