The output intensity of optically pumped NH3 molecules far-infrared laser(N
H3-OPFIRL) was calculated by solving the density matrix equation and by mea
ns of iteration method. Meanwhile, the spectral characteristic of AC Stark
splitting was studied. Finally, the the F-P interferogram of NH3-OPFIRL pum
ped by CO2-10R(8) line was measured. The experimental results were in good
agreement with the theoretical calculation results.