| 摘要 |
PURPOSE:To always perform a stable amplification irrespective of the polarization state of exciting light from a light source for excitation. CONSTITUTION:Exciting light from a laser 22 for excitation is changed into unpolarized light by an unpolarized-light generation part 11, and the unpolarized light is made incident on an optical branching and-multiplexing device 23. In the optical-branching and-multiplexing device, an optical signal which is incident via an optical isolator 24 is multiplexed with the exciting light, and multiplexed light is radiated to a rare-earth-doped optical fiber 21. Since the exciting light is the unpolarized light at this time, the propagation loss of the light-branching and-multiplexing device is not changed, and the exciting light whose intensity is definite is incident on the rare-earth-doped optical fiber. The exciting light is propagated through the rare-earth-doped optical fiber, and it excites rare-earth elements. An optical signal which is propagated through the rare-earth-doped optical fiber due to an induced emission by the excited rare-earth elements is amplified, and an amplified optical signal is radiated to the outside via an optical isolator 25. |
