Reversible supramolecular chiral structures induced in azopolymers by elliptically polarized light: influence of the irradiation wavelength and intensity

Abstract

Photoinduced supramolecular chiral structures in azo materials have been extensively studied for the development of all-optical switches and because of their influence on the properties of certain types of polarization holographic gratings. Here, we investigate chiral structures induced by irradiation with elliptically polarized light in thin films of four azopolymers denoted as PAZO, P 1 , P 1 − 2 , which are amorphous, and P 2 , which is liquid crystalline. Their formation is characterized in real time by the kinetics of azimuth rotation. The influence of the irradiation wavelength and intensity is also analyzed. The largest azimuth rotation per unit thickness is achieved in PAZO (33°/µm) and P 1 − 2 (25°/µm). Reversibility of the chiral structures is demonstrated by a tenfold change in the direction of rotation. Our results also indicate that chiral structures formation occurs significantly faster than the induction of linear birefringence.

Polarization Diffraction Gratings in PAZO Polymer Thin Films Recorded with Digital Polarization Holography: Polarization Properties and Surface Relief Formation

“…In recent decades, there has been increasing scientific interest in polarization-sensitive photoanisotropic materials, due to their unique applications in polarization holography, and in photonics, as a media for the reversible optical storage of information and polarization multiplexing [14,15], for creating polarization-selective optical elements [16][17][18], for structures with surface modulation with high spatial frequency [19,20], to create optical switches [21,22], and more. Azobenzene-containing materials are commonly used organic materials for polarization holographic recording due to the high values of photoinduced anisotropy upon illumination with polarized light [10].…”