Theoretical and experimental examination of PQ-PMMA photopolymer material

Abstract

Phenanthrenequinone (PQ) doped poly(methyl methacrylate) (PMMA) photopolymer material has been studied extensively due to the growing interest in application involving photopolymers. However, to progress the development a more physical material model has become necessary. In this article, a kinetic model is developed, which includes: (i) the time varying photon absorption, including the absorptivity of a second absorber, i.e., the singlet excited state of PQ, (ii) the recovery/regeneration and the bleaching of the excited state PQ, (iii) the nonlocal effect, and (iv) the diffusion effects of both the ground and excited state PQ molecules and of the methyl methacrylate (MMA). A set of rate equations are derived, governing the temporal and spatial variations of each chemical component concentration. The validity of the proposed model is examined by applying it to fit experimental data for PQ-PMMA layers containing three different initial PQ concentrations, i.e., 1 mol.%, 2 mol.% and 3 mol.%. The effect of different exposure intensities is also examined. Material parameters are extracted by numerically fitting experimentally measure normalized transmission curves and the refractive index modulation growth curve using the theoretical models.