| 초록 |
Optical properties such as refractive index, birefringence, thermal stability and optical loss of fluorinated co-poly(arylene ether sulfide)s, co-poly(arylene ether sulfone)s and photosensitive polyimides were investigated and they are related to the molecular structure of the polymers. The refractive index of the optical polymers varies in the range of 1.51 to 1.60 and its variation is well described by the Lorentz-Lorenz equation. The birefringence varies between 0.0027-0.0039 for the sulfide series and between 0.0009-0.0025 for sulfone series at 1.55 ㎛ wavelength, respectively. The birefringence is analyzed based on the microscopic anisotropic ratio of the polarizability of the molecular repeating unit resulting in good linear relationship between them within the polymer groups. This result implies that the molecular calculation can be utilized to design polymers with low birefringence. Especially, the photosensitive polyimides with a chalcone group for photocrosslinking by UV exposure have zero birefringence, resulting from the increasing kinked group after photocrosslinking. The propagation losses are 0.1-0.3 dB/cm at 1.3 ㎛ and 0.2-0.5 dB/cm at 1.55 ㎛ wavelength for sulfide and sulfone series, and they are 0.14 dB/cm at 1.3 ㎛ and 0.33 dB/cm at 1.55 ㎛ wavelength for photosensitive polyimides, respectively. The optical losses are inversely proportional to fluorine content. The polymers have good thermal stability upon long-term thermal stress at 100 ℃ for 1000 h and short-term thermal stress at 300 ℃ for 1 h.
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