Feasibility of radiation wavefront correction in the case of pulsed operation of a laser with a plane–plane resonator

It is shown that in the case of plane-plane resonator lasers with a short growth time of the lasing process the divergence of the output radiation can be reduced by correcting the wavefront with a positive lens. Experiments confirm a reduction in the divergence by a factor of about 2 in the case of a barium nitrate crystal Raman laser and a rhodamine 6G laser. The geometric-optics approximation is used for a II-shaped pump pulse of duration τ to demonstrate analytically that the correcting lens has a focal length F ≈ cτ near the lasing threshold.