PLASTIC OPTICAL FIBER

PROBLEM TO BE SOLVED: To provide a refractive index distribution type optical fiber having suppressed initial transmission loss and loss increase upon bending and enhanced heat resistance and wet heat resistance, and having a non-crystalline fluorine-containing polymer which has no C-H bond as its material. SOLUTION: In the refractive index distribution type optical fiber having concentric inner and outer at least two layer structure, an inner layer has an amorphous fluorine-containing polymer (a) substantially having no C-H bond as its material; an outer layer comprises an amorphous fluorine-containing polymer substantially having no C-H bond, has a refractive index lower than that of the outermost part of the inner layer and comprises only a fluorine-containing polymer (d) obtained by polymerizing a monomer, containing a compound represented by formula (1) or a fluorine-containing polymer material (c) to be a mixture of the fluorine-containing polymer (d) and an another material. The formula (1) is CF2=CF-O-CR1R2-CR3R4-CF=CF2. In the formula, R1, R2, R3and R4each independently denotes F, CF3or OCF3and at least one among them denotes CF3or OCF3. COPYRIGHT: (C)2011,JPO&INPIT