LIGHT-INDUCED ORIENTATION IN AZO-POLYIMIDE POLYMERS 325-DEGREES-C BELOW THE GLASS-TRANSITION TEMPERATURE

We report on light-induced nonpolar orientation of sidechain nonlinear -optical polyimides [glass transition temperatures (T-g) up to 350 deg rees C] containing no flexible connectors or tethers. The nonlinear-op tical azo-dye chromophore is incorporated through the donor substituen t as a part of the polymer backbone. This impressive photoinduced orie ntation occurs at room temperature, i.e., at least 325 degrees C below the T-g of one of the polymers that we investigated. Furthermore, it is shown that, after photoinduced ordering, this polymer must be heate d to 350 degrees C to induce main-chain movement and to erase the orie ntation, whereas the direction of orientation of the chromophores can easily be controlled at room temperature simply by choice of the appro priate polarization of the irradiating light. This light-induced orien tation process is shown to be useful for storing images in waveguides. (C) 1997 Optical Society of America.