| 摘要 |
PURPOSE:To offer parts simple in structure and having a wide field distribution of exciting light and high amplification efficiency by connecting an optical fiber which has a larger core diameter to one of optical fibers connected to a joined part. CONSTITUTION:The optical fiber 15 is connected to the optical fiber 12 of a port D among ports A-D. This optical fiber 15 consists of a core part 15a and a clad part 15b and the core part 15a has a diameter larger than the core diameter of the core part 12a of the optical fiber 12. When propagated light is made incident from the port A and the exciting light is made incident from the port D, the exciting light form an inverted distribution of optical amplifying substance ions at a small-diameter part 14 and the propagated light is amplified by this inverted distribution and projected from the port B or/and port D. Consequently, the exciting light is made incident from the optical fiber 15 which has the larger core diameter, so the field distribution of the exciting light is wide and the exciting light is propagated to the whole amplifying clad part at the small-diameter part 14, thereby forming the inverted distribution of almost all the optical amplifying element ions effectively. |
