ANALYTICAL DESCRIPTION OF THE OPTICAL-FIELD IN A CIRCULAR FIBER ARRAY WITH KERR-LAW NONLINEARITY

The propagation characteristic of nonlinear normal modes in a circular fibre array with Kerr nonlinearity is investigated in detail by two different methods, a continuous approximation of the envelope of the slowly-varying amplitudes and a numerical solution of the coupled-mode equations for the discrete amplitudes. In the framework of both approaches we calculate the propagation constants and the field profiles of particular nonlinear envelope normal modes. It turns out that even in the weak nonlinear case both entities depend on the guided power which applies normally for large nonlinearities.