Novel cyclophosphazenes containing aryl trifluorovinyl ether functional units together with the corresponding perfluorocyclobutane (PFCB) phosphazene polymers have been synthesized and characterized. These polymers have desirable properties for low optical loss waveguide applications. The monomers used in this study were prepared from sodium 4-(trifluorovinyloxy)phenoxides and cyclophosphazenes with fluorinated alkoxy or aryloxy side groups. The resulting polymers, produced by 2π + 2π cyclopolymerization of the aromatic trifluorovinyl ether moieties, showed good chemical stabilities and high thermal stabilities (Td up to 330 °C). Tough and transparent thin films of these polymers were readily prepared by solvent-free processes using spin-coating of the monomers. By adjusting the ratio of monomers, the refractive index of the polymers could be controlled from 1.4528 to 1.5187 at 1550 nm, with exceptionally low birefringence of Δn = 0 to 0.0003 ± 0.0002. A propagation optical loss lower than ∼0.25 dB/cm at ...