| 摘要 |
PURPOSE: To suppress the connection loss for both signal light and excitation light in the connecting section of a rare-earth-element-doped optical fiber of an optical fiber amplifier which uses the rare-earth-element-doped optical fiber as a gain medium with another optical fiber. CONSTITUTION: The normalizing frequencies of a rare-earth-element-doped optical fiber 12 and another optical fiber constituting an optical fiber type coupler 11 connected to the fiber 12 are set to the same value. An dopant which is easily diffused when it is heated is added to both fibers 11 and 12 and the mode field diameters of the fibers 11 and 12 are matched to each other by enlarging the diameters of the fibers at the connecting section of the fibers by diffusing the dopant. |
