Pulse duration and angular distribution of submicrosecond radiation from a flashlamp-pumped dye laser

An experimental investigation was made of the angular divergence of radiation from a laser in which a rhodamine 6G solution was subjected to flashlamp pumping and emitted pulses of 220–750 nsec duration. The divergence was practically independent of the pulse duration and when the resonator base was varied within the length 240–3000 mm, it decreased from 2.8 to 0.7 mrad. These results demonstrated that macroscopic inhomogeneities did not develop during a pump pulse in the dye solution, but the divergence exceeded the values expected solely due to the scattering by microinhomogeneities of the medium. The experimental results were explained by postulating noise radiation in the active medium of density estimated to be half the density of the scattered laser radiation.