Stimulated Raman Scattering in Pb(MoO₄)_1−x(WO₄)_x with x = 0, 0.5, 0.8 and 1.0 with Combined Frequency Shifts on High- and Low-Frequency Raman Modes under Synchronous Picosecond Laser Pumping

Comparative characteristics of spontaneous and stimulated Raman scattering in Pb(MoO4)1−x(WO4)x single crystals (x = 0, 0.5, 0.8, and 1.0) including both the high (ν1) and low (ν2) frequency internal anionic group vibrations have been investigated. It was found that among these crystals, Pb(MoO4)0.2(WO4)0.8 is the most suitable for multi-wavelength Raman laser in several Raman modes simultaneously. This is caused by the optimal relative Mo/W content corresponding to the most efficient coherent combination of the (MoO4)2− and (WO4)2− vibrations enhancing the output radiation characteristics of the synchronously pumped Pb(MoO4)0.2(WO4)0.8 Raman laser. Oscillation of up to twelve, closely spaced SRS components in a range of 1128–1360 nm and the strongest pulse shortening down to 1.16 ps in comparison with not only PbMoO4 and PbWO4 but also with all the earlier investigated nominally pure scheelite-like tungstate and molybdate crystals has been achieved

Stimulated Raman Scattering in Pb(MoO4)1−x(WO4)x with x = 0, 0.5, 0.8 and 1.0 with Combined Frequency Shifts on High- and Low-Frequency Raman Modes under Synchronous Picosecond Laser Pumping

Comparative characteristics of spontaneous and stimulated Raman scattering in Pb(MoO4)1−x(WO4)x single crystals (x = 0, 0.5, 0.8, and 1.0) including both the high (ν1) and low (ν2) frequency internal anionic group vibrations have been investigated. It was found that among these crystals, Pb(MoO4)0.2(WO4)0.8 is the most suitable for multi-wavelength Raman laser in several Raman modes simultaneously. This is caused by the optimal relative Mo/W content corresponding to the most efficient coherent combination of the (MoO4)2− and (WO4)2− vibrations enhancing the output radiation characteristics of the synchronously pumped Pb(MoO4)0.2(WO4)0.8 Raman laser. Oscillation of up to twelve, closely spaced SRS components in a range of 1128–1360 nm and the strongest pulse shortening down to 1.16 ps in comparison with not only PbMoO4 and PbWO4 but also with all the earlier investigated nominally pure scheelite-like tungstate and molybdate crystals has been achieved

Structure and thermal expansion of Ca9Gd(VO4)7\mathrm{Ca_{9}Gd(VO_{4})_{7}}: A combined powder-diffraction and dilatometric study of a Czochralski-grown crystal

Materials of the Ca$_9$RE(VO$_4$)$_7$ (CRVO) formula (RE = rare earth) and whitlockite-related structures are considered for applications in optoelectronics, e.g., in white-light emitting diodes and lasers. In the CRVO structure, the RE atoms are known to share the site occupation with Ca atoms at two or three among four Ca sites, with partial occupancy values depending on the choice of the RE atom. In this work, the structure and quality of a Czochralski-grown crystal of this family, Ca$_9$Gd(VO$_4$)$_7$ (CGVO), are studied using X-ray diffraction methods. The room-temperature structure is refined using the powder diffraction data collected at a high-resolution synchrotron beamline ID22 (ESRF, Grenoble); for comparison purposes, a laboratory diffraction pattern was collected and analyzed, as well. The site occupancies are discussed on the basis of comparison with literature data of isostructural synthetic crystals of the CRVO series. The results confirm the previously reported site-occupation scheme and indicate a tendency of the CGVO compound to adopt a Gd-deficient composition. Moreover, the thermal expansion coefficient is determined for CGVO as a function of temperature in the 302–1023 K range using laboratory diffraction data. Additionally, for CGVO and six other single crystals of the same family, thermal expansion is studied in the 298–473 K range, using the dilatometric data. The magnitude and anisotropy of thermal expansion, being of importance for laser applications, are discussed for these materials