| 摘要 |
PURPOSE:To obtain the core material which is less increased in optical transmission loss by an external pressure by incorporating a specific repeating unit into this material. CONSTITUTION:This core material is formed of the org. silicon polymer or copolymer contg. the repeating unit expressed by formula I or formula II. In the formulas I, II, substituents R<1> to R<4> are respectively 1 to 10C, more preferably 1 to 6C univalent hydrocarbon groups and include, for example, alkyl groups, such as methyl group, ethyl group and propyl group, a phenyl group, etc. Substituents P, Q are respectively 6 to 20C, more preferably 6 to 15C bivalent arom. hydrocarbon groups. The core material which is less increased in the optical transmission loss by the external pressure is obtd. in this way. |
