Fine structure of Surface Relief Gratings: experiment and a generic stochastic Monte Carlo model of the photoinduced mass transport in azo-polymer

TL;DR

This paper combines experimental observations with a stochastic Monte Carlo model to analyze the fine structure of Surface Relief Gratings in azo-polymer, revealing detailed mechanisms of photoinduced mass transport.

Contribution

It introduces a novel Monte Carlo model for photoinduced mass transport in azo-polymers and demonstrates the transport of polymer chains from bright to dark regions.

Findings

Double-peak SRG maxima can develop in various regimes.

The model predicts different SRG structures depending on material properties.

Experimental and theoretical results agree on the transport mechanism.

Abstract

We study experimentally and theoretically a double-peak fine structure of Surface Relief Gratings in azo-functionalized poly(etherimide). For the theoretical analysis we develop a stochastic Monte Carlo model for photoinduced mass transport in azobenzene functionalized polymer matrix. The long sought-after transport of polymer chains from bright to dark places of the illumination pattern is demonstrated and characterized, various scenarios for the intertwined processes of build-up of density and SRG gratings are examined. Model predicts that for some azo-functionalized materials double-peak SRG maxima can develop in the permanent, quasi-permanent or transient regimes.