Spatial and temporal characteristics of the radiation from a high-power XeCl laser with an unstable telescopic resonator

The radiation characteristics of an XeCl laser with a 30-liter active medium were investigated as a function of the magnification of an unstable telescopic resonator. Optimal resonator magnifications minimized the divergence at half the radiation energy (M = 18) and ensured the highest radiation brightness in the far-field zone (M = 8.5). When an unstable telescopic resonator was used, the radiation pulses were modulated in the far-field zone and the modulation period was a multiple of the resonator round-trip time for the radiation. The depth of modulation increased with M. The time of formation of the transverse resonator modes increased as their order became lower and decreased with M for the lowest-order modes. The width of each of the lasing lines due to the 0–1 and 0–2 transitions was 25 pm for M = 8.5.