Functional Optical Data Storage

Fig. 16. Maximum achievable signal-to-noise ratio (SNR) on read-out of different writable optical data storage systems as a function of the writing energy (laser power) (121). SQS = Organic dye system (WORM) PC = phase change system (TeSeSb) MO = magnetooptical system (GbTbFe). See text.

Weener et al. prepared photo-responsive monolayers from azobenzene modified polypropylene imine) dendrimers which also hold promise in the area of optical data storage [74], A fifth generation polypropylene imine) dendrimer was functionalized with equal amounts of palmitoyl and azobenzene containing alkyl chains, resulting in the formation of an amphiphilic copolymer with a random shell structure (Figure 16.5). 

Breiner T (2001) Block coplymers with functionalized poly(2-hydroxyethyl methacrylate) segments for optical data storage. PhD Thesis, University of Bayreuth... 

Aligned LC molecules are proven to be useful in many apphcations ranging from the well-known LCDs, to lenses [39], shutters and components used in optical data storage [38]. For proper functioning of all these applications the control of the alignment of the LC molecules is of crucial importance. 

We have prepared multi-component photorefractive polymers for optical data storage applications (8). This photorefractivity is a combination of two functionalities electro-optic effect and photoconductivity. We have achieved holographic diffraction efficiencies up to >30% in our composites. 

Nowadays most colorants have the purpose to satisfy our aesthetical needs and, thus, thousands of dyes and pigments are produced on industrial scales. Nevertheless, nearly periodically new demands arise for so-called fimctional dyes whose tt-conjugated systems exhibit novel functionahties beyond aesthetical purposes. Optical brighteners or near-infrared absorbers are examples where even transparency in the visible spectrum is desired and dyes for nonlinear optics, holographic optical data storage and two photon absorption are further examples where the color properties of dyes are insignificantly related to the functional demands. 

In addition, it has been demonstrated that such molecularly designed polymers with narrow polydispersities can be used for further functionalization or crosslinking reactions and exploited for fabricating optical data storage, electrooptic displays and nonlinear optical systems (Percec and Tomazos 1992). 

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