| 摘要 |
PURPOSE:To provide an optical amplifier which can be used for two-way transmission in the same wavelength band and, at the same time, has a simple constitution. CONSTITUTION:This optical amplifier is constituted of a four-terminal light circulator 4 which has forward characteristics from a terminal A to a terminal B, from a terminal C to a terminal C, and from the terminal D to the terminal A, optical multiplexer 3 connected between the terminals B and C, and optical amplifier circuit composed of a rare-earth-added optical fiber 1 and excitation light source 2 which is connected to the multiplexer 3 and makes excitation light incident to the optical fiber 1. |
