Photoinduced alignment of azobenzene moieties in the side chains of polyglutamate films

✍ Scribed by Z. Sekkat; M. Büchel; H. Orendi; H. Menzel; W. Knoll

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 436 KB
• Volume: 220
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(94)00195-2

✦ Synopsis

The 'transHcis' reversible photoisomerization process tends to align azobenzene derivatives perpendicular to the polarization direction of the pumping beam. It is shown that in the trans-rcis optical transition the cis state is aligned perpendicular to the pumping light polarization. This is shown for spin-coated films of 'hairy-rod' polyglutamate with azobenzene moieties in the side chains. Photoselection in both trans and cis states is demonstrated using the attenuated total reflection method.

Recently much interest has focused on polymers doped or functionalized with photochromic dyes for integrated optics. Azobenzene derivatives are a family of dye molecules that are well known for their reversible 'trans*cis' photoisomerization in solution and in polymer films [ 1 ] #I. Linearly polarized pump light creates refractive index anisotropy or dichroism for probe beams with wavelengths falling respectively outside or inside the absorption band of the photosensitive molecules. The photoinduced anisotropy and dichroism were widely studied in the sixties by Neporent et al. [ 21 in viscous solutions. Later these properties were used by Todorov et al. [ 31 in polymer films for polarization holography applications. Recently many authors have been interested in azodye doped or functionalized polymers for writingerasing optical memories [ 4-6 1, for building optical channel waveguides [ 7 ] and for inducing second-or-* Corresponding author. s' This review paper contains a large bibliography on photoisomerization.