Proceedings Article | 17 August 1998
KEYWORDS: Composites, Chromophores, Polymers, Nonlinear optics, Diffraction, Glasses, Electro optics, Diffraction gratings, Birefringence, Molecules
Three-component is a promising direction to overcome disadvantages (e.g., unstability and critical environment requirement) of the four-component low glass transition temperature photorefractive (PR) polymer composite which consists of photosensitizer, nonlinear optical (NLO) chromophore, charge transport agent, and the plasticizer separately. Based on the well-known hole photoconductive network of poly(N-vinylcarbazole):2,4,7-trinitro-9-fluorenone, in our presented investigations, several well-performanced three-component PR composites were developed for different application purposes with the optimal designing optical chromophore exhibit both NLO response and plasticizing property. Generally, it is expected that long chain alkoxy of the chromophore may increase the plasticizing property while long alkoxy chain makes itself more easy to curl, which might weaken the plasticizing function, thus an optimum selection ofthe length ofthe alkoxy exists. From the experimental observations of 2,5-dimethyl-4-(4'—nitrophenylazo)benzene with different length of the alkoxy, it was indicated that high coupling gain (—195 cm') and index grating amplitude (—.4.3x1O) were achieved at 633nm in the composite contain l-n-butoxyl-2,5-dimethyl-4-(4'_nitrophenylazo)benzene. Besides, different substituent groups make the chromophore inequal plasticizing and different electrooptic properties. For operating at short wavelength, 3,3-diacety1-4methoxylstyrene is the more suitable selection (with a coupling gain of—38cm' at 543 urn, which is higher than these at 593 nm, 612nm and 633 urn). Doped with f3,f-diacety1-4-methoxylstyrene, a response time as short as —17 ms at illumination intensity of 1 W/cm2 at the wavelength of 633 nm was estimated, which is the most fast response reported up to now and can be used in real-time optical information processing. On the other hand, all composites mentioned above have long lifetime and high stability
Key words: phtorefractive, polymer, three-component, grass transition temperature, coupling gain, real-time hologram
