A compact Raman laser gas spectrometer is developed. It comprises a high-power green laser at 532.123 nm as an excitation source and a specially designed gas cell with an internal volume of less than 0.6 cm3 that can withstand gas pressures up to 100 atm. The resolution of the spectrometer is ~1 cm−1. The Raman spectra of chemically pure isotopically enriched carbon dioxide (12CO2, 13CO2) and methane (12CH4, 13CH4) gases are studied. The expected limit of detection (LOD) is less than 100 ppm for the isotopologues of CO2 and less than 25 ppm for those of CH4 (at a gas pressure of 50 atm.), making the developed spectrometer promising for studying the sources of emissions of greenhouse gases by resolving their isotopologue composition. We also show the suitability of the spectrometer for Raman spectroscopy of human exhalation.

Polycrystalline zinc sulfide (ZnS) samples obtained by chemical vapour deposition were doped with Cr 2+ ions using hot isostatic pressing (at 100 MPa/1250 °C). Their structure was studied by means of x-ray diffraction, SEM and Raman spectroscopy. The Cr 2+ :ZnS samples exhibited excellent transparency in the near-IR. Absorption saturation of Cr 2+ :ZnS is demonstrated at 1.54 µm ( 5 T 2 ( 5 D) → 5 E( 5 D) transition of Cr 2+ ions in tetrahedral sites) for ns-long pulses yielding a saturation fluence of 0.16 ± 0.03 J cm −2 . The laser-induced damage threshold is 6.0 ± 0.5 J cm −2 . The synthesized polycrystalline Cr 2+ :ZnS is promising for passive Q-switching of erbium lasers emitting at 1.5-1.7 µm.

Transparent glass-ceramics (GCs) containing Co:Mg(Al,Ga)₂O₄ nanocrystals (mean diameter of 7-9 nm) are synthesized by heat treatments at 850-950°C from magnesium aluminosilicate glass nucleated by TiO₂ and doped with Ga₂O₃ and CoO. The GCs exhibit a broadband A₂4(F4)→T₁4(F4) absorption due to the Co²⁺ ions, low saturation fluence (∼0.5  J/cm²), fast recovery time of initial absorption (∼300  ns), and high laser damage threshold (∼20  J/cm²). They are used for passive Q-switching of a diode side-pumped Er,Yb:glass laser generating 3.1 mJ/20 ns pulses (peak power, 155 kW) at 1535 nm with a TEM₀₀ output mode. The Q-switching performance of the Co:Mg(Al,Ga)₂O₄-based GCs is compared with that for various Co²⁺-doped GCs and Co:MgAl₂O₄ single crystal. The prepared GCs are promising for further applications in passively Q-switched Er:YAG and other Er crystalline (or ceramic) lasers.

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