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.