Generation of optical fields with a periodic travelling intensity profile in a wide-aperture laser with a bleachable filter

A theoretical investigation was made of the dynamics of generation of an optical field in a Fabry — Perot cavity with an active medium and a bleachable filter, considered in the limiting case of an infinitely large aperture. The approximation of a point model was used to describe the cavity, the model equations were solved, and the lasing regimes were classified. More interesting are those regimes in which the field loses its homogeneity and a self-oscillatory modulation of the field appears along the aperture, so that the point model is inapplicable. These regimes were investigated by introducing a self-oscillatory variable into the equations, which makes it possible to dispense with partial derivatives. A theory of nonlinear oscillations can be used to determine the characteristics of wave perturbations (velocity, period, amplitude) near the boundary of a steady-state region; this was done analytically and numerically. Purely harmonic periodic solutions and solutions of an arbitrary type were found. The results showed that an increase in the bifurcation parameter may result in a transition from a periodic wave pattern to a chaotic one, and that this can occur in accordance with various scenarios.