Reversible and irreversible alterations of the optical thickness of PQ/PMMA volume recording media samples. Part 2:...

A theoretical study of phenanthrenequinone-doped polymethyl methacrylate (PQ/PMMA) samples parameter changes during irradiation is presented. The research has been carried out on the basis of the experimental study (Part 1, [Appl. Opt.56, 7351 (2017)APOPAI0003-693510.1364/AO.56.007351]) and a mathematical model that describes space-time reversible and irreversible light-induced changes of the PQ/PMMA sample parameters during exposition. Based on the numerical modeling results and the use of analytical dependencies, a number of practically important characteristics of the PQ/PMMA sample-exposure process are considered: conversion-induction period of phenanthrenequinone into a photoproduct, Δt_ind; bleaching time of a sample, t_bl; and thermal nonlocality of photoresponse, δl_T. It is shown that the values Δt_ind and t_bl are on the order of tens and hundreds of seconds, respectively, and can be comparable to the exposure time. It is established that temperature increase leads to δl_T value change by hundreds of nanometers and can cause considerable deformation of the interference structure under recording. The sample heating during exposition is considered in detail, and an algorithm for estimation of the maximum temperature increase to be used in experiments is proposed. Recommendations are made for the reduction of negative influence of sample heating on the parameters of recorded holograms.