Characteristics of iodine laser short-pulse amplifier

An investigation was made of the energy balance of a free-oscillation iodine amplifier pumped with light generated by a high-current discharge in the active gas. Some of the pump energy was absorbed in a shock wave traveling ahead of an expanding discharge plasma. Optical inhomogeneities in the amplifying layer were investigated. A transverse gradient of the refractive index in this layer could reach 10⁶ cm^–1. The magnetic field of the discharge influences strongly the laser emission spectrum, shifting it by 0.2 cm^–1 during a pulse and broadening it to 0.3 cm^–1. When the discharge current passed through zero, the stimulated emission was due to the unperturbed F = 3 → F' = 4 transition in the hyperfine structure of the iodine atom. Thus, a short pulse could be amplified at the moment the current passed through zero.