Revision on the calculation of optically pumped FIR laser spectrum with Doppler broadening and pressure broadening effects

By means of iteration method and also taking into account Doppler broadening and pressure braodening effect of IR pumping laser, the output power density of optically pumped NH₃ molecules FIR laser is calculated by solving density matrix equations of three-level system. The results of theoretical calculation shows that, in comparison with the FIR laser under the assumption of ideal monochromatic IR pumping, the output power density of FIR laser in the case of Doppler broadening and pressure broadening IR pumping decreases much more. Meanwhile, via the revision of Doppler broadening and pressure broadening effect, the theoretical value of optimum operating gas pressure reduces, which is in better agreement with the experimental value. Further study shows that the revision of Doppler broadening effect is more fit for the conventional FIR laser with a 2m sample tuble and the revision of pressure broadening effect is much more suitable for the miniature FIR laser with a short sample tube of 5 to 20cm in length.