Modeling the Diffraction Efficiency of Reflective-Type PQ-PMMA VBG Using Simplified Rate Equations

A simulation based on the rate equations was performed to analyze the concentration distribution of molecules in phenanthrenequinone (PQ) doped polymethyl methacrylate (PMMA) polymers (PQ-PMMAs) exposed using a two-beam interference configuration. The concentration distributions were used to predict the diffraction efficiency of PQ-PMMA-based volume Bragg gratings (VBGs) by using the transfer matrix method. The simulation results suggest that an intermittent exposure method can promote the diffusion of PQ molecules and increase the final diffraction efficiency. A series of experiments validated our hypothesis that the diffraction efficiency of reflective-type PQ-PMMA VBG can be predicted.