In this Letter, we demonstrate the pulsed and CW operation of the $\mathrm{Dy}\text{:}{\mathrm{PbGa}}_2{\mathrm{S}}_4$ laser directly pumped by the 1.7 μm laser diode. In the pulsed regime (pulse duration 5 ms; repetition rate 20 Hz), the maximum mean output power of 9.5 mW was obtained with the slope efficiency of 9.3% with respect to the absorbed pump power. The generated wavelength was 4.32 μm, and the laser beam cross section was approximately Gaussian on both axes. Stable CW laser generation was also successfully obtained with the maximum output power of 67 mW and the slope efficiency of 8%. Depopulation of the lower laser level by 1.7 μm pump radiation absorption followed by 1.3 μm upconversion fluorescence was demonstrated. These results show the possibility of construction of the compact diode-pumped solid-state pulsed or CW laser generating at 4.3 μm in the power level of tens mW operating at room temperature.

The Fe:Zn(1-x)Mg(x)Se (x = 0.19, 0.27, and 0.38) solid solutions spectroscopic properties were investigated and laser oscillations were achieved for the first time. The increase of the magnesium concentration in the Fe:ZnMgSe crystal was shown to result in an almost similar long wavelength shift of both absorption and fluorescence spectra of about 60 nm per each 10% of magnesium. With the Fe:ZnMgSe crystal temperature decrease, the fluorescence spectrum maximum shifts towards shorter wavelength resulting mainly from strong narrowing of the longest wavelength fluorescence line. Laser radiation wavelength dependence on the magnesium concentration as well as on temperature was observed. The Fe:ZnMgSe x = 0.38 laser oscillation wavelength increased from 4780 nm at 80 K to 4920 nm at 240 K using the optical resonator without any intracavity spectrally-selective element. In comparison with the Fe:ZnSe laser operating in similar conditions, these wavelengths at both temperatures were shifted by about 500 nm towards mid-IR region.

The room-temperature laser-oscillation properties of lead thiogallate crystals doped with dysprosium ions $\mathrm{Pb}{\mathrm{Ga}}_2{\mathrm{S}}_4:{\mathrm{Dy}}^{3+}$ without additional codoping and codoped with potassium ion for excessive charge compensation were investigated. A slope efficiency of 1% was obtained for the codoped crystal. YAP:Er $-1.66\mu \mathrm{m}$ laser resonant pumping of $\mathrm{Pb}{\mathrm{Ga}}_2{\mathrm{S}}_4:{\mathrm{Dy}}^{3+}$ laser was compared with YAG:Nd $-1.32\mu \mathrm{m}$ nonresonant pumping. The maximum energy obtained was $57\mu \mathrm{J}$ with the negligible influence of the atmosphere.