US Patent 7903975 Optical add-drop multiplexer
Patent 7903975 was granted and assigned to Hitachi (Japanese train) on March, 2011 by the United States Patent and Trademark Office.
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A problem to be solved in an optical communication system for carrying out bidirectional transmission between communication nodes by wavelength-division-multiplexed optical signals is that a plurality of optical add-drop multiplexers installed in the communication nodes are required for each transmission direction, and therefore, the communication cost is increased. An optical circulator or an optical coupler is arranged at an input/output port of the optical add-drop multiplexer and the wavelength-division-multiplexed optical signals are assembled for each transmission direction, whereby optical signals transmitted bidirectionally can be handled by one optical add-drop multiplexer.
US Patent 07903975 Optical add-drop multiplexer US Patent 7903975 Optical add-drop multiplexer
US Patent 07903975 Optical add-drop multiplexer
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