Fig. 1. Optical scheme of the experiment: 1, 5, CO₂ laser rear mirrors; 2, EBSD CO₂ laser chamber; 3, 7, 9, plane-parallel BaF₂ plates; 4, plane-parallel ZnSe plate; 6, diffraction grating; 8, 22, spherical mirrors; 10, photodetector; 11, power and energy meter; 12, 21, flat mirrors; 13, lens; 14, gas cell input window; 15, gas input channel; 16, output to pressure meter; 17, mirrors of THz cavity; 18, Mylar film; 19, parabolic mirror; 20, quartz plate; 23, detector of THz radiation.

Fig. 2. Pulses of CO₂ laser (bottom) and NH₃ laser (top) pumped by the line 9R(16). E_pulse = 0.59 J.

Fig. 3. Pulses of CO₂ laser (bottom) and NH₃ laser (top) pumped by the line 9R(30). E_pulse = 0.91 J.

Fig. 4. Dependence of the NH₃ laser pulse duration τ_pulse and the delay time τ_delay on the CO₂ laser pulse energy for the pump lines 9R(16) and 9R(30).

Fig. 5. Spectrum of THz emission obtained for the pump CO₂ laser line 9R(30); ammonia pressure 2.5 mbar.

Fig. 6. Dependence of the NH₃ laser output with a wavelength of 90.4 µm on the CO₂ laser pulse energy for the 9R(16) pump line at ammonia pressure of 10.0, 5.5, 3.0, and 2.0 mbar.