Spatial-Temporal Dynamics of Self-Trapping Waveguides in Photopolymer Absorbing Layers with Competing Nonlinearities

Abstract

The dynamics of the formation of 3D light self-trapping waveguides in a volume photopolymeric medium, namely polymethyl methacrylate (PMMA) with photosensitive phenanthrenequinone (PQ)-molecules, has been studied theoretically and experimentally. The di˙erent contributions of two competing nonlinear mechanisms with the formation of the photoproduct and with the heating of the medium due to absorption have been analyzed. To describe the propagation dynamics of laser beams in the photopolymeric material, a theoretical model has been proposed including heat conduction and di˙usion equations in conditions of spatially inhomogeneous light-induced heating of the medium together with the kinetic equations for the photoreactions which proceed within the photopolymeric material. The principal patterns for the spatial and temporal dynamics of the formation of 3D self-trapping waveguides in thick absorbing layers of PQ-PMMA with concurrent nonlinear mechanisms have been established theoretically and verified experimentally.