Numerical simulation of Bessel-Gauss light beams in crystals with quadratic nonlinearity

With the developed method of numerical simulation, the dynamics of formation of the spatial structure of interacting wave fields in the process of generation of the sum-frequency radiation was investigated. Radial intensity profiles and angular spectra of diffracting light beams with varied restriction and focusing parameters at different stages of energy exchange in the KTP crystal have been calculated. It is shown that with weak focusing, a self-channeling wave structure of soliton type with angular divergence of the second-harmonic component at the level close to the diffraction limit is formed in the field of the wide Bessel-Gauss pumping beam. Moreover, in the far-field zone complete spatial separation of the light fluxes corresponding to the fundamental and second harmonics occurs. Comparison of the efficiencies of conversion on pumping by Gauss and Bessel-Gauss light beams is made. ©2005 Springer Science+Business Media, Inc.