Very large electro-optic coefficients from in situ generated side-chain nonlinear optical polymers

A synthetic/processing method has been developed for achieving highly efficient nonlinear optical polymers. A maleimide-containing chromophore with large molecular nonlinearity was covalently attached onto a anthrathene- containing polymer to generate in situ a side-chain polymer via the Diels-Alder reaction. The poling and covalent side-chain attachment processes can be performed simultaneously in a solid state, resulting in high electro-optic (E-O) coefficients (r₃₃ values up to 50 pmV at 1310 nm) and temporal stability (85% retention of the original dipole alignment after isothermal heating at 85 °C for more than 500 h). A very high chromophore loading level (39 wt %) can be achieved by adding more chromophore into this side-chain polymer without causing any obvious phase separation. Poling of this chromophore-doped side-chain polymer (total dye content: 34 wt %) showed a significantly increased E-O coefficient, from 50 to 110 pmV.