Transverse pattern formation and spectral characteristics of cw light beams in resonant media: an improved numerical simulation technique and mode analysis

Abstract

We suggest an improved numerical algorithm for nonlinear paraxial optics that makes use of the modified quasi-fast-Fourier–Bessel transform and the special high-harmonic correction technique. The algorithm is applied to an initially cw near-resonance Gaussian beam propagating through a strongly saturated two-level medium. The spatial behavior is in good agreement with experiments and simulations by other authors. The spectral characteristics, which to our knowledge have not been previously studied, are shown to be drastically affected by the transverse pattern formation. The semianalytical approach of our earlier research is shown to provide a sufficient approximation of the beam, requiring only a few of the lowest-order dressed Laguerre–Gaussian modes.