| 摘要 |
PURPOSE:To reduce the signal distortion of an optical signal to be transmitted and to reduce the fluctuation of transmission light intensity by the phase noise of a light source by providing media (media with different wavelength dispersion values) with propagation speed different depending on wavelength. CONSTITUTION:Incident wavelength multiplex input light is demultiplexed to two beams of light by an optical coupler 11. and they are propagated through the media 13-1, 13-2 with different wavelength dispersion values. For example, assuming that the wavelength dispersion value of the medium 13-2 on one side shows zero. the light with every kind of wavelength is provided with the same propagation speed in the medium 13-2, and actual wavelength in the medium is proportional to input wavelength. Since different propagation speed of every kind of wavelength are provided in the medium 13-1 provided with wavelength dispersion, the actual wavelength in the medium is not proportional to the input wavelength. In an optical coupler 12 with which the light is interfered, the phase difference of two beams of input light is different depending on the wavelength, therefore, the light with selected wavelength is outputted. Since difference of optical path length between two routes operated as wavelength filters is scarcely recognized, the distortion of the optical signal can be reduced. |
