Study of the output beam spatial characteristics of a cascade Raman laser with multimode diode pumping

We report a study of the spatial characteristics of the beam output from a multimode-pumped SRS cascade laser. The intensity profiles of transmitted pump radiation beams, as well as of the first and second orders Stokes SRS generation, is measured in two different laser configurations: in a classical laser with two pairs of reflectors and in a scheme with a half-open cavity for the second order Stokes component. The dynamics of changes in the intensity profiles of the radiation beams in the two considered resonators is shown to differ significantly. The data obtained for the beam profiles are analysed together with the power characteristics of the cascade Raman laser within the framework of a balance model of interaction between pump radiation and the Stokes components of the SRS.