STATIONARY EMISSION AND STABILITY OF A DETUNED CASCADE LASER

The stationary emission and stability of a three-level cascade laser i n which two fields of different frequencies can be simultaneously ampl ified is investigated under conditions of cavity detuning. Different m onomode and bimode solutions are found and analysed for the effects of different pitchfork and Hopf bifurcations. At moderate cavity detunin gs, features different from those observed in other classes of lasers are found, such as for instance a decrease in the instability threshol d when detuning is introduced. Particular attention is paid to the cas e of resonance of the two-photon transition, which allows us to study the continuous evolution, when detuning is increased, of a resonant ca scade laser towards a pure two-photon laser. In particular, this estab lishes the origin of some features which are characteristic of two-pho ton lasers.