Experimental studies on a tunable efficient high-efficient pulsed NH<sub>3</sub> terahertz (THz) lasers pumped by TEA CO<sub>2</sub> lasers
are presented. When NH<sub>3</sub> is pumped by the different lines with the CO<sub>2</sub> lasers, the generation of different terahertz
radiations is discussed. The lines of the CO<sub>2</sub> lasers are 9R(08), 9P(20), 10R(14), 10R(08), and 10R(06). To improve THz
laser energy and photon conversion efficiency, different higher power of the CO<sub>2</sub> laser can effectively improve THz laser
energy and photon conversion efficiency. When the 9P(20) CO<sub>2</sub> lasers with 9.68 J and 4.12 J pump NH<sub>3</sub>, the
corresponding energy conversion efficiencies are 0.28% and 0.19%, increasing by a factor of about 1.5. The generation
of terahertz radiations with energy as high as 27.29 mJ and 7.73 mJ are obtained, respectively, increasing by a factor of
about 3.5. Meanwhile, for 10R(14) line, the energy conversion efficiencies increase to 8.5 times and the energy of THz
lasers increase to 32 times.
Triethylamine (C6H15N) is widely used to stabilize the discharges of wavelength-nonselective transversely excited atmospheric (TEA) CO2 lasers. In this paper, the influences of triethylamine on the discharge stability and line characteristics of a high-energy wavelength-selective TEA CO2 laser are experimentally studied. The laser has 49 lasing lines ranging from 9.23 μm to 10.74 μm, and the energy of the strongest lines is above 50 J. However, the energy of the laser pulses is very unstable. The discharge stability is improved considerably by adding small amounts of triethylamine in the working gas mixture. In addition, lines in the 9 μm band are weakened greatly, and many of them even can no longer oscillate. In contrast, there are no distinct influences on the 10 μm lines. The results obtained in this study demonstrate the applied range of triethylamine in stabilizing the discharges of wavelength-selective CO2 lasers.