Intrinsic hyperpolarizability of 3-dicyanomethylene-5,5-dimethyl-1-[2-(4-hydroxyphenyl)ethenyl]-cyclohexene nanocrystallites incorporated into the photopolymer matrices

Second-order optical properties of anionic 3-dicyanomethylen-5,5-dimethyle-1-[2-(4-hydroxyphenyl)ethenyl)]-cyclohexene (1) with crystalline sizes from 10 nm to 300 nm were studied. An electric field enhancement of effective second-order susceptibility at 1064 nm for the crystallites incorporated into the oligoetheracrylate photopolymer matrices from 3.1 pm/V to 7.8 pm/V was discovered corresponding to hyperpolarizability increase from 0.12 × 10−30 esu to 0.21 × 10−30 esu. The evaluated intrinsic hyperpolarizability achieves value about 0.037, which is comparable with the best organic molecule. Principal possibility of enhancing the intrinsic hyperpolarizability was achieved by applying an external electric field and decrease of the nanocrystallite sizes without an increase of the π-conjugated bond numbers.