Photoinduced Anisotropy Peculiarities of Holographic Gratings Recorded in PEPC-co-SY3 Azopolymer

Abstract

In this work, we studied the photoinduced polarimetric and optical properties of the photosensitive carbazole-based azopolymer prepared in the form of thin films. Poly-N-(2,3-epoxypropyl)carbazole was used as a polymer matrix, which was copolymerized with the commercially available azo dye Solvent Yellow 3. Thin films of µm thicknesses were obtained by home-made rod-coating techniques. Polarization holographic recording was applied for direct diffraction gratings patterning. The polarization states of the recording beams were P–P, S–S, ±45° and left-right circular. The optical path of the probe beam passing through investigating media is defined by the summary changes in surface topography and volume anisotropy. The periodically modulated polarization/amplitude interference patterns produced by the gratings were investigated by in situ measurements of the diffraction efficiency (DE) kinetics in the first diffraction order at the DE saturation value. The surface relief was measured by AFM. A comparison of the behavior of azopolymer films during the recording of diffraction gratings with different polarization configurations of recording beams was carried out. The presented results confirm the possibility of recording not only the amplitude and phase of light, as in scalar holography, but also the polarization states of interfering beams. The angular dependences of the probe beam azimuth and ellipticity were analyzed, and some peculiarities of azopolymer photoinduced changes are discussed.