INSTABILITIES IN DOPPLER BROADENED OPTICALLY PUMPED FAR-INFRARED LASERS F. LAGUARTA, J. PUJOL, R. VILASECA and R. CORBALAN J. Phys. Colloques, 49 C2 (1988) C2-409-C2-412 DOI: 10.1051/jphyscol:1988297