Effect of inhomogeneities of an active medium on the divergence of radiation from a long-pulse electric-discharge XeCl laser

The effect of optical inhomogeneities of the active medium of an electric-discharge XeCl laser excited by 300-ns pulses on the divergence of amplified radiation is experimentally studied. The possibility of obtaining the diffraction-limited divergence of radiation at the output of the amplifier is shown. Under our conditions, for the pump power density exceeding 400 kW cm^-3 , the radiation divergence in mainly determined by the nonuniformity of the gain profile of the active medium that appears at a certain stage of the discharge burning. This property of the active medium is caused by the development of macro- and microinhomogeneities of the discharge current.