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The technique of pumping is utilized widely to analyze the tunable continuous wave and femtosecond mode-locked laser operation of the [Yb.sup.3+] molecule in the tetragonal NaLu[(W[O.sub.4]).sub.2] crystal host. The results show that the host crystal exhibits several attractive laser properties that are induced due to the inhomogeneous broadening of the Yb spectral features.

Cu 2 ZnSn 1− x Ge x S 4 (CZTGS) thin films prepared by flash evaporation of a Zn-rich Cu 2 ZnSn 0.5 Ge 0.5 S 4 bulk compound in powder form, and a subsequent thermal annealing in S containing Ar atmosphere are studied. The effect of the substrate temperature during evaporation and the initial composition of the precursor powder on the growth mechanism and properties of the final CZTGS thin film is investigated. The microstructure of the films and elemental depth profiles depend strongly on the growth conditions used. Incorporation of Ge into the Cu 2 ZnSnS 4 lattice is demonstrated by the shift of the relevant X-ray diffraction peaks and Raman vibrational modes towards higher diffraction angles and frequencies respectively. A Raman mode at around 348–351 cm −1 is identified as characteristic of CZTGS alloys for x =[Ge]/([Sn]+[Ge])=0.14−0.30. The supply of Ge enables the reduction of the Sn loss via a sacrificial Ge loss. This fact allows increasing the substrate temperature up to 350 °C during the evaporation, forming a high quality kesterite material and, therefore, reducing the deposition process to one single stage. [ABSTRACT FROM AUTHOR]