| 摘要 |
PURPOSE:To stably amplify optical signals in two directions by a single optical amplifier when signal light is amplified in the middle way of a bidirectional optical communication line. CONSTITUTION:The wavelength of the two beams of signal light propagated in two directions can be multiplexed/demultiplexed by an optical multiplexer/ demultiplexer, and they are made as the one with different wavelength in the amplification wavelength range of an erbium doped optical fiber amplifier. Since an optical isolator is always required for stable optical amplification, such constitution is employed that a light propagation line where two beams of signal light are propagated separately is formed at a part of optical amplifier by combining optical multiplexer/demultiplexers 208, 209, 210, and 211, and the optical isolators 212, 213 are inserted in the propagation line. Thereby, one directivity is provided between the input/output terminals 216, 217 of the optical amplifier for the signal light with the wavelength on one side and that with the wavelength on the other side, respectively, however, every beam of light can be propagated in the two directions in the erbium doped optical fiber 201 in which the signal light and excitation light function mutually. |
