Kinetics of diffraction gratings formation in a polymer matrix containing azobenzene chromophores: Experiments and Monte Carlo simulations

Abstract

The physical processes accompanying an illumination of azobenzene chromophores embedded in a polymer matrix with spatially modulated and linearly polarized light are studied experimentally and simulated using the Monte Carlo (MC) method. The MC simulations base on a simple three-channel kinetic model of trans-cis type photoisomerization cycles in azobenezene molecules. The method focus on studying the kinetics of diffraction grating recording and erasing under various conditions of illumination, light polarization and recording in the presence or absence of a background light. By modeling the “macroscopic” light diffraction efficiency one gets insight into the role played by microscopic processes (angular hole burning, angular redistribution, rotational diffusion) up to the high-temperature limit, characterized by a high mobility of polymer chains. The obtained qualitative agreement between experimental data and the modeling confirms that the main processes underlying grating recording and erasing are well identified. The experimentally observed two-exponential functional dependence of diffraction efficiency η as function of time is well explained by the MC modeling.

Holographic grating recording in azobenzene functionalized polymers

“…The square root of diffracted power can be used to gain insight into the primary processes of light induced refractive index and absorption changes. The temporal dependencies of the square root of diffracted power signals were fitted using a double-exponential growth function: are the recording time constants of the fast and slow grating build-up processes contributing [38,39]. The decomposition of typical temporal evolution of grating recording into fast and slow contribution is shown in Fig.…”

Monte Carlo Based Design of Photonic Processes in Azopolymers

“…[14][15][16], which is a generalisation of an athermal model [13]. The model which describes the polymer matrix with doped azodyes, has three parameters related to physical processes enumerated in the Introduction: p c!t ; p t!c ; p diff .…”

“…The kinetics of diffraction gratings formation and erasure in a polymer matrix doped with azo-dyes can be effectively studied by Monte Carlo approach, using a kinetic model [13] generalised onto the temperature-dependent case [14]. This approach was recently used to model some temperature independent [13] and temperaturedependent phenomena [15,16].…”

“…This approach was recently used to model some temperature independent [13] and temperaturedependent phenomena [15,16]. In particular, preliminary Monte Carlo studies of temperature-controlled inscription of gratings in azopolymers, based on an analogy with an opto-thermal writing used in magnetooptic storage [17], were presented in Ref.…”

Curing behaviour of epoxy resins with a diamine bearing an azobenzene group

“…where τ 1 and τ 2 describe time constants of two different grating build-up processes [28]. A and B parameters describe the contribution of these processes to diffraction of light on the grating.…”