| 摘要 |
PURPOSE:To obtain titled resin clad optical fiber with large effective NA (numerical aperture) by providing an intermediate layer of doped quartz between a quartz core and a resin clad, and equalizing its refractive index to that of the core at the boundary part between the layer and core and decreasing the refractive index outwardly. CONSTITUTION:The core 1 is made of pure quartz and the clad layer 2 is made of silicone resin; and the intermediate layer 3 is provided between both. This intermediate layer is deposited B2O3 having about 10mum thickness and made of quartz doped by a CVD method, and this layer is equal in refractive index to the core where it contacts thereto and decreases gradually to the outside. Those layers are represented on an (r) axis (lateral axis) and the refractive indexes are represented on an (n) axis (longitudinal axis). Consequently, titled optical fiber has 0.5 fiber NA, 0.3 effective NA, and 4 dB/Km loss. Namely, light leaking out of the core is returned to the core by the intermediate layer having the low refractive index, so light in high-order mode is less attenuated and the effective NA is improved, so that cracking becomes harder to occur to the boundary part. |
