Abstract
A cw CO2 laser operating on the R(30) 9-μm transition is downshifted by 180 MHz in a pair of acousto-optic modulators to give an exact coincidence with the sR (5, 0) transition in NH3. The downshifted radiation optically pumps mixtures of NH3 in N2 and creates vibrational inversion in the ν2 mode of NH3. This inversion is monitored with a tunable-diode laser operating in the 11–12-μm region. Gain coefficients as large as 3.4%/cm are measured in the P branch of the ν2 band, and the measured gain coefficients are found to be in good agreement with a rate-equation model based on rotational thermalization. Detailed measurements of gain coefficients are presented as a function of NH3 transition, pump power, and gas mixture and pressure. These results will aid in the optimization of cw NH3 lasers operating in the 11–13-μm region.
© 1985 Optical Society of America
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