Kinetics of saturation of the active medium of an oxygen-iodine laser

A theoretical study is made of the dependences of the gain for the ²P_1/2(F= 3)→²P_3/2(F' = 4) transition in the iodine atom on the intensity of the incident field and also on the rate constants of the processes occurring in the active medium of an oxygen-iodine laser. The main processes that determine the kinetics of saturation by the incident field are the exchange of the electronic energy between iodine atoms and oxygen molecules, translational relaxation of iodine atoms, van der Waals mixing of the sublevels of ²P_3/2, and also mixing of the sublevels of ²P_1/2 in the course of exchange interaction with oxygen molecules. It is shown that the translational and hyperfine relaxation processes play an exceptionally important role in the establishment of the emission spectrum. The influence of the anomalous dispersion effects on the divergence of laser radiation in the multimode lasing regime is discussed. A finite translational relaxation rate reduces severalfold the output power of an oxygen-iodine laser and increases the length of the lasing zone in the downstream direction.