A series of novel fluorinated poly(aryl ether)s containing phthalazinone moieties (FPPEs) have been prepared by a modified synthetic procedure for optical waveguide applications. The obtained random copolymers exhibited excellent solubility in polar organic solvents, high glass transition temperatures (T(g)s: 185-269 degrees C), good thermal stabilities (the temperatures of 1% weight loss: 487-510 degrees C) and good optical properties. By adjusting the feed ratio of the reactants, the refractive indices of TE and TM modes (at 1550 nm) could be well controlled in the range of 1.575-1.498 and 1.552-1.484, respectively. The optical losses of the FPPEs exhibited relatively low values (less than 0.27 dB/cm at 1310 nm). Additionally, the thermo-optic coefficient (dn/dT) values of the FPPEs at 1310 nm and 1550 nm (TE mode) ranged from -0.97 x 10(-4) C to -1.33 x 10(-4) degrees C and from -0.96 x 10(-4) degrees C to -1.29 x 10(-4) degrees C, respectively. (C) 2008 Elsevier Ltd. All rights reserved.