Photorefraction charge-transport agents

In earlier investigations by the author [1,2] an additional nonlinear optical chromophore, (IV), and charge transport agent, (V), respectively, were prepared and used in photorefractive applications. 

A series of photorefractive poly(methacrylate)s, containing a Disperse Red-type chromophore and carbazole as the charge transport agent with various spacer lengths, was synthesized and characterized. The photorefractive effect of these materials was studied by four-wave mixing and two beam coupling at 780 nm after sensitization with 1% (2,4,7-trinitroflu-... 

Within a relatively short time, many polymeric materials were developed that do exhibit the photorefractive effects. These materials consist of polymers with charge transport agents and photosensitizing dyes. The quantity of change in a material s refractive index that is altered by alterations in an applied electric field is expressed as the electrooptic coefficient r. Lithium niobate has an r value of 30 pm / volt. Several polymers are already known that possess coefficients (at 1.3 pm) greater than 30 pmW and the aim now is to develop materials with r values of 50 pm / volt or even higher. It is also known that the photorefractive effect can also be observed in many organic materials. 

One photorefractive polyimide 59 was formed by linking thee units, a substituted porphyrin (charge generator), 4-amino-4 -nitrostilbene derivative (the nonlinear optics molecule), and a charge transporting agent, pyromellitic dianhydride. This polyimide retains its nonlinear optical properties even after... 

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