The spatial structure of Raman-converted radiation was investigated numerically and experimentally for the case when the pump is a conical beam produced by an axicone from multimode laser radiation. Both conical and axial Stokes beam generation was found to be possible. The improvement of the laser beam quality was demonstrated numerically and supported by experiment on Raman conversion in barium nitrate crystal. The laser beam with the beam quality factor M<sup>2</sup>=11 was converted into the axial Stokes beam with M<sup>2</sup>=3.5 at the conversion efficiency of 20%. A two-times increase in the Stokes beam brightness was obtained.
© 2006 Optical Society of America
Original Manuscript: August 15, 2005
Revised Manuscript: November 25, 2005
Manuscript Accepted: December 14, 2005
Ruslan V. Chulkov, Alexander S. Grabtchikov, Dmitry N. Busko, Pavel A. Apanasevich, Nikolai A. Khilo, and Valentin A. Orlovich, "Beam quality improvement at Raman conversion of multimode conical beam," J. Opt. Soc. Am. B 23, 1109-1116 (2006)