Spectroscopic, laser, and χ⁽³⁾ nonlinear optical properties of tetragonal PbWO₄, NaY(WO₄)₂, CaWO₄, and monoclinic CdWO₄ and ZnWO₄ were investigated. Particular attention was paid to Nd³⁺-doped and undoped PbWO₄ and NaY(WO₄)₂ crystals. Their absorption and luminescence intensity characteristics, including the peak cross sections of induced transitions, were determined. Pulsed and continuous-wave lasing in the two ⁴ F _3/2→ ⁴ I _11/2 and ⁴ F _3/2 →⁴ I _13/2 channels was excited. For these five tungstates, highly efficient (greater than 50%) multiple Stokes generation and anti-Stokes picosecond generation were achieved. All the observed scattered laser components were identified. These results were analyzed and compared with spectroscopic data from spontaneous Raman scattering. A new crystalline Raman laser based on PbWO₄ was developed for the χ⁽³⁾ conversion frequency of 1-µm pump radiation to the first Stokes emission with efficiency up to 40%. We classify all the tungstates as promising media for lasers and neodymium-doped crystals for self-stimulated Raman scattering lasers.

We report the first observation of anti-Stokes laser-induced cooling in the ${\mathrm{Er}}^{3+}:{\mathrm{KPb}}_2{\mathrm{Cl}}_5$ crystal and in the ${\mathrm{Er}}^{3+}:\mathrm{CNBZn}$ (${\mathrm{CdF}}_2\mathrm{\text{−}}{\mathrm{CdCl}}_2\mathrm{\text{−}}\mathrm{NaF}\mathrm{\text{−}}{\mathrm{BaF}}_2\mathrm{\text{−}}{\mathrm{BaCl}}_2\mathrm{\text{−}}{\mathrm{ZnF}}_2$) glass. The internal cooling efficiencies have been calculated by using photothermal deflection spectroscopy. Thermal scans acquired with an infrared thermal camera proved the bulk cooling capability of the studied samples. The implications of these results are discussed.

The optical properties of ${\mathrm{Nd}}^{3+}$ ions in six different compositions of glasses based on ${\mathrm{GeO}}_2,$ PbO, and ${\mathrm{Bi}}_2{\mathrm{O}}_3$ have been investigated by using steady-state and time-resolved laser spectroscopy. Judd-Ofelt parameters were derived from the absorption spectra and used to calculate the ${}^4{\overrightarrow{F_{3/2}}}^4{I}_{11/2}$ stimulated emission cross section and the ${}^4{F}_{3/2}$ radiative lifetime. Site-selective spectroscopy and time resolved fluorescence line narrowing experiments were performed in the ${}^4{\overrightarrow{F_{3/2}}}^4{I}_{9/2}{,}^4{I}_{11/2}$ transitions. For all samples studied a line narrowing of the ${}^4{\overrightarrow{F_{3/2}}}^4{I}_{11/2}$ emission has been observed when exciting at the long wave side of the ${}^4{\overrightarrow{I_{9/2}}}^4{F}_{3/2}$ transition. The lifetimes of the ${}^4{F}_{3/2}$ state do not show a monotonic variation with the excitation wavelength indicating large site-to-site variations in the local crystal field. Spectral migration of excitation among the ${\mathrm{Nd}}^{3+}$ ions has been studied from the time evolution of the ${}^4{\overrightarrow{F_{3/2}}}^4{I}_{9/2}$ spectra under resonant excitation. The results can be interpreted in terms of a dipole-dipole energy transfer mechanism. Visible upconversion has been observed in these glasses under infrared laser excitation.

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