Experimental results are reported on the nonlinear interaction of a 0.5 μm laser light with long scalelength preformed plasmas. Spectra from stimulated Brillouin and Raman scattering, as well as measurements of the transmitted laser light clearly indicate the occurence of strong nonlinearities driven by filamentation of the laser beam.
Willi, O., Basset, D., Giulietti, A., & Karttunen, S. (1989). Nonlinear interaction of an intense laser beam with millimetre sized underdense plasmas. Optics Communications, 70(6), 487-492. https://doi.org/10.1016/0030-4018(89)90370-2