| 摘要 |
PURPOSE:To obtain the beam expanding fiber which has small loss even when bent by providing a 1st and a 2nd specific clad outside a core. CONSTITUTION:This fiber is a single-mode fiber consisting of the core 11 with a 8mum diameter, the 1st clad 12 with a 40mum diameter, and the 2nd clad with a 125mum diameter. The core 11 is made of quartz glass doped with germanium dioxide, the 1st clad 12 is made of quartz glass doped with fluorine F, and the 2nd clad 13 is made of undoped quartz glass. Then the specific refractive index difference between the core 11 and 1st clad 12 is 0.3% and the specific refractive index difference between the 1st clad 12 and 2nd clad 13 is 0.3%. Consequently, even if the optical fiber is curved at a part where the mode field diameter is increased, light is prevented from exiting from the fiber because of the refractive index difference between the 1st clad 12 and 2nd clad 13. |
