Single axial-mode operation of the pulsed far-infrared p-Ge laser with an i
ntracavity Fabry-Perot type frequency selector has been observed by means o
f Fourier-transform spectroscopy. A spectral resolution better than 1 GHz h
as been achieved on an ordinary continuous-scan spectrometer using the even
t-locked technique for pulsed emission sources. A laser active-cavity fines
se of at least unity has been directly confirmed from the measured emission
spectral width. Analysis of the envelope of the corresponding interferogra
m suggests that the finesse exceeds 10. (C) 2000 American Institute of Phys
ics. [S0003-6951(00)00215-1].