| 摘要 |
PROBLEM TO BE SOLVED: To suppress level fluctuation for each wavelength by demultiplexing signal light received through an optical transmission line for each wavelength, adjusting the gain of the signal for each separated wavelength, rotating each polarization plane of each signal light whose gain is adjusted and totally reflecting each output signal light so as to reduce the polarization wave dependence. SOLUTION: A WDM coupler 3 demultiplexes a wavelength multiplex signal received from a multiplex port 31 for each wavelength and outputs them from demultiplex ports 321-32N. The light outputs from the demultiplex port 321-32N are respectively reflected in total reflection plates 611-61N via variable optical attenuators 411-41N and Faraday rotators 511-51N corresponding to the light signals, and propagated through the reverse path. Since the Faraday rotators 511-51N have a function of rotating the polarization plane by 45 degrees, the polarization plane of the output light signals is rotated by 90 degrees with respect to the incident polarized waves. Then the light signals with the polarization planes orthogonal to each other pass through the attenuators 411-41N and the WDN coupler 3 to average the polarized wave dependence of the optical components. |
