| 摘要 |
PURPOSE:To compensate a light quantity loss of a transmission line by amplifying light which is not subjected to wavelength dispersion by diffraction efficiency of a diffraction grating and returning it to the transmission line by amplifying a '0'-order light by a light amplifier. CONSTITUTION:Light subjected to wavelength multiplexing by wavelength lambdaa-lambdac from an input fiber 11 is made incident on a diffraction grating 15 through a lens 13. By the diffraction grating 15, the light of the wavelength lambdaa-lambdac is subjected to wavelength dispersion by a ratio of diffraction efficiency of the diffraction grating 15 and coupled to photodetecting fibers 12a-12c, respectively through the lens 13. On the other hand, light which is reflected without being subjected to wavelength dispersion, that is, a '0'-order light is made incident on a light amplifier 16 through a lens 14. The '0'-order light is amplified by the light amplifier 16 and its output light is guided to an output fiber 17. Accordingly, the greater part of light from a transmission line is subjected to optical demultiplexing by the diffraction grating 15, and by amplifying the remaining '0'-order light and returning it to the transmission line, a light loss is eliminated, and for instance, the limiting of the number of terminals which can be installed in an optical loop LAN can be eliminated. |
