Simple modelling of nonlinear losses induced by Kerr lensing effect

Abstract

This paper considers the calculation of the nonlinear losses induced in a circular aperture enlighten by a focused Gaussian beam (GB) subject to optical Kerr effect. Such a problem known since a long time typically requires the numerical calculation of a diffraction integral which becomes rapidly cumbersome in the case of repetitive applications. Alternatively, we propose a new simple modelling completely analytical. This method called as Non Gaussian Gaussian Beam modelling is based on the beam propagation factor $$M^{2} > 1$$\n of the GB traversing the Kerr aberration. The $$M^{2}$$\n is found to depend only on the nonlinear Kerr phase shift and independent of the wavelength and the width of the GB incident on the Kerr medium. This simple modelling has been applied to three applications: Kerr Lens Mode locking (KLM) mechanism, optical limitation, and Z-scan technique for a large nonlinearity.