Reversible Optical Storage in Azo Polymers

Amorphous high-Tg azobenzene-containing polymers can be used as reversible information storage materials in form of films. The procedure takes advantage of the photochemically activated trans-cis-trans isomerization of the azobenzene groups. The written information is stable below the polymer glass transition temperature. Writing and erasing can be performed up to 105 times on the same spot or the polymer film. The reorientation mechanism depends on the type of substituents bound to the azobenzene group, on the type of the neighboring group on the polymer chain and on the tendency of the polymer to self-organize. The efficiency of the process depends on the maximum absorbance of the azobenzene group and can be tailored to reach unity. This property of azobenzene-containing polymers can be used in optical and holographic memory, waveguides and sensors, and photonic devices.