Mode structure of a resonator with non-Gaussian components. II. Multipass off-axial structures

A study is made of the mode structure of a resonator containing a component with non-Gaussian optical inhomogeneities. Use is made of geometric optics to show that, in addition to the traditional axial structure, fundamentally new non-Gaussian mode systems can appear in a non-Gaussian resonator. The new systems include multipass off-axial structures. It is shown that the behaviour of multipass modes is governed not only by the nature of aberrations, but also by the configuration of the resonator system. An analytic method for calculations relating to multipass modes is described. The results of the investigation are illustrated by a large number of numerical modelling examples.