Effects of cooperative atomic behavior on lasers

The effect of cooperative behavior, both with respect to pumping and relaxation, on a number of three-level atomic systems which are assumed to have a dipole moment at all three transition frequencies, is analyzed. The atoms are coupled to two cavity modes resonant at the two intermediate frequencies and pumped coherently at the highest frequency. For sufficiently strong pumping, three steady states are shown to exist, the stability of which depends on the pumping strength and the cavity losses. Transition from one steady state to another produces modulated field pulses in both modes, with the phase of the modulation envelopes as well as the phase of the fields being synchronized. Conditions for the generation of various types of pulses are investigated. A generalization that takes into account pump losses due to atomic reaction is introduced and the effect of these losses is studied.