| 摘要 |
<p>A refractive index profile type optical fiber having a multi-layer structure in which a plurality of non-mixed layers (LNB1-LNBm) of copolymers (P1-Pm) with glass transition temperatures (Tg) of 80 °C or higher are laminated concentrically, the copolymers (P1-Pm) being selected from the group consisting of one or more kinds of homopolymers (HP1, HP2, ... and HPn) (wherein the refractive indices of these homopolymers decrease in that order) each comprising two or more kinds of vinyl monomers (M1, M2, ... and Mn), and copolymers (CP) comprising M1, M2, ... and Mn units, and having a refractive index which is highest at the central portion of the multi-layer structure and decreases progressively toward the peripheral portion. This optical fibers has a low transmission loss, a large numerical aperture and an excellent moist heat resistance.</p> |
