Low-loss polymer optical waveguides with high thermal stability

We synthesized novel cross-linkable fluorinated copoly(arylene ether sulfide) for optical waveguide applications, which have high thermal stability, high optical transparency in the infrared communication region, and much smaller birefringence than other thermally stable fluorinated polyimides. The refractive index of the material can be easily controlled from 1.515 to 1.587 by changing the copolymer composition in the materials. The birefringence of the cured polymers were 0.0031∼0.0039 at the wavelength of 1.55 μm. This is much lower than those of fluorinated polyimides for optical waveguides. The refractive index of fluorinated poly(arylene ether sulfide) (FPAESI) after being stored at 100 °C for 1000 hr remains almost constant demonstrating the thermal stability. The propagation loss of the channel waveguides fabricated using reactive ion etching was less than 0.4 dB/cm at the wavelength of 1.55 μm.