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.

We demonstrate a diode-pumped master oscillator power amplifier Nd:YAG 1064 nm laser with sub-joule-level output energy of 0.43 J, high pulse repetition rate of 200 Hz, and short pulse duration of 100 ps. The 5 mJ master oscillator consisted of a 100 nJ/100 ps Nd:YVO microchip laser and end-pumped Nd:YAG regenerative amplifier. The two-pass output amplifier was based on two ∅10×140  mm Nd:YAG laser rods. We apply an adaptive compensator with an analyzer based on an astigmatic optical system and a quadrant photodiode to compensate for low-order wave-front non-stationary thermal distortions in a high-energy laser amplifier. The adaptive compensator demonstrates high sensitivity to curvature changes of λ/100, and it provides output beam divergence near 1.5×DL in 100 ps 0.43  J×200  Hz of operation mode.

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