Fluorinated ether ketone oligomers bearing a crosslinkable ethynyl group at the chain end have been investigated for low-loss polymer optical waveguide devices. These oligomers are designed to achieve low birefringence and were synthesized by the reaction of 4,4Ј-(hexafluoroisopropylidene)diphenol with an excess decafluorobenzophenone, followed by reaction with (phenylethynyl)phenol or ethynylphenol. The molecular weights (M n s) and polydispersities of the oligomers determined by GPC with polystyrene standard are in the range of 6600 -8500 g/mol and 1.79 -2.04, respectively. By spin coating and thermal crosslinking, the polymer solutions easily provide the good optical quality thin films. The cured films show good chemical resistance and high thermal stability up to 460°C under nitrogen. At 1.55 m wavelength, the refractive index and birefringence of the films show in the range of 1.5104 -1.5172 and 0.0078 -0.0014, respectively. The propagation loss of the single-mode channel waveguide was measured to be less than 0.5 dB/cm at 1.55 m.

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