Investigation of local optical inhomogeneities in flashlamp–pumped photodissociation lasers

An experimental study was made of the local changes in the refractive index during lasing in the active medium of a flashlamp-pumped iodine photodissociation laser. There were no local inhomogeneities in regimes with storage of the population inversion and disruption of lasing by strong quenching. It was found that the laser emission inhomogeneity over the active medium was of regular nature with a radiation-density modulation of 20–30% and a characteristic inhomogeneity scale length of $\lesssim$ 0.5 mm. On the basis of these experimental results and of theoretical estimates it was concluded that the local optical inhomogeneities were caused by gasdynamic displacements of the gas due to different amounts of heat released in the regions of muximum and minimum radiation density.