Time dynamics of a family of opto-thermal nonlinear devices is described by means of a system of linear partial differential equations subjected to a nonlocal and nonlinear boundary condition and a rich variety of homoclinic phenomena is numerically found. Linear-stability analysis shows that the effective dynamical dimension is determined by the device structure, i.e. by the number of layers between two mirrors, and then it may be easily varied. A variety of local and global bifurcations observed in bilayer systems are described in detail, showing that the dynamics is in effect two-dimensional except for subtle features appearing in a gluing bifurcation where two homoclinic connections occur almost simultaneously. Complex behaviour is shown to occur in the case of trilayer systems, with a very similar dynamics to the one of the well-known Rössler model of third-order ordinary differential equations. Two different families of aperiodic phase portraits are described in detail and their association with homoclinic connections to saddle invariant sets of different configurations is pointed out. The occurrence of complex dynamics is demonstrated by means of first-return 1D maps obtained in proper Poincaré sections. © 1995.