| 摘要 |
PURPOSE:To allow the selective passage of the light signal of a required wavelength from a wavelength multiplex light signal without depending on polarization by making the light signal subjected to a wavelength sepn. In a wavelength separating circuit to plural rare earth element-added optical fiber amplifier circuits, then guiding the light signal to an optical multiplexing circuit. CONSTITUTION:The wavelength multiplex light signal subjected to an attenua tion effect during propagation in an optical fiber 1 is separated by each wave length in the wavelength separating circuit 4 and is made incident to the optical fiber amplifier circuits 6-1 to 6-n. Exciting light amplifies the light signal when the exciting light is made incident from a light source 5 to the optical fiber amplifier circuits 6-1 to 6-n at this time. The degraded intensity is then recovered and the light is emitted from the optical fiber amplifier circuits 6-1 to 6-n. The light signal is not emitted from the optical fiber amplifier circuits 6-1 to 6-n if the exciting light is not made incident to the optical fiber amplifier circuits 6-1 to 6-n and, therefore, the light signal of the one wavelength lambda1 is selected from, for example, the wavelength multiplex light signal and is taken out to the light receiving circuit 3 via the optical multiplexing circuit 7. |
