| 摘要 |
PURPOSE:To provide the optical filter which not only separates light having the same wavelength component according to its power, but also has superior long-period stability, can be handled while putting in a core and coupled with an optical fiber for transmission with ease and is matched with communication wavelength. CONSTITUTION:The inside of the core of the quartz-based optical fiber or the peripheral part of the core is doped with a rare earth element and the density stripe length product (CL) which is the product of the doping amount of the rare earth element and the length of the optical fiber is present in a range encircled with respective curves satisfying Pexin=10<(>CL</22)> and Pexin=10<(>CL</45)>, where Pexin is the power of exciting light to the rare earth element. |
