Birefringence induced in azopolymer (PAZO) films with different thickness

In this article we present a study of the photoinduced birefringence (Δn) in films of a water soluble azopolymer: poly[1- [4-(3-carboxy-4-hydroxyphenylazo)benzenesulfonamido]-1,2-ethanediyl, sodium salt] (PAZO). Varying the concentration of the azopolymer in the solution, films with wide range of thicknesses are obtained – from 50 to 2500 nm. The film thickness is determined with a Talystep precision profilometer. Birefringence is measured using a polarimetric setup with a recording laser at 473 nm and probe He-Ne laser at 633 nm. As shown experimentally, the maximal photoinduced birefringence (Δnmax) does not depend on the thickness and is of the order of 0.07 for all of the investigated samples. The recording time however considerably increases for films thicker than 500 nm.

[1]  D. Karashanova,et al.  Increase of photoinduced birefringence in a new type of anisotropic nanocomposite: azopolymer doped with ZnO nanoparticles. , 2012, Optics letters.

[2]  Manfred Eich,et al.  Reversible digital and holographic optical storage in polymeric liquid crystals , 1987 .

[3]  A. Matharu,et al.  Photoinduced anisotropy in a family of amorphous azobenzene polyesters for optical storage. , 2003, Applied optics.

[4]  S. Hvilsted,et al.  Peptide oligomers for holographic data storage , 1996, Nature.

[5]  T. Todorov,et al.  Polarization holography. 1: A new high-efficiency organic material with reversible photoinduced birefringence. , 1984, Applied optics.

[6]  P. Sharlandjiev,et al.  Anisotropic hybrid organic/inorganic (azopolymer/SiO2 NP) materials with enhanced photoinduced birefringence. , 2013, Applied optics.

[7]  S. Xie,et al.  Azo polymers for reversible optical storage. 2. Poly[4'-[[2-(acryloyloxy)ethyl]ethylamino]-2-chloro-4-nitroazobenzene] , 1992 .

[8]  S. Xie,et al.  Azo polymers for reversible optical storage. Ill. Effect of film thickness on net phase retardation and writing speed. , 1993, Applied optics.

[9]  Ludmila Nikolova,et al.  Characteristics of high-efficiency polarization holographic gratings , 2001, International School on Quantum Electronics: Laser Physics and Applications.

[10]  A. Matharu,et al.  Liquid crystals for holographic optical data storage. , 2007, Chemical Society reviews.

[11]  Ezeddin Mohajerani,et al.  Morphological and thickness analysis for PMMA spin coated films , 2007 .

[12]  T Todorov,et al.  Spectrophotopolarimeter: fast simultaneous real-time measurement of light parameters. , 1992, Optics letters.

[13]  Marina Saphiannikova,et al.  Photosensitive response of azobenzene containing films towards pure intensity or polarization interference patterns , 2014 .

[14]  Maria Raposo,et al.  Long-term stability at high temperatures for birefringence in PAZO/PAH layer-by-layer films. , 2012, ACS applied materials & interfaces.

[15]  T. Fukuda,et al.  Optical and Physical Applications of Photocontrollable Materials: Azobenzene-Containing and Liquid Crystalline Polymers , 2012 .