Toward submicrometer optical storage through controlled molecular disorder in azo-dye copolymer films

While information encoding through optically induced orientation of azo dyes in organic matrices is being extensively pursued, we propose the alternative of starting out with poled films and to locally reduce their second-harmonic generation capacity by a focused near-infrared femtosecond laser beam of moderate intensity. Arrays of dots irradiated under varying conditions are subsequently imaged in situ as dark spots on a bright background. The samples are also examined through conventional optical microscopy and through atomic force microscopy. We demonstrate that, of these techniques, second-harmonic imaging performs best in the task of information retrieval.