Patent ID: 7903975
Filing Date: 2011-03-08
Classification: H04J

Abstract:
1. An optical add-drop multiplexer for dropping an optical signal having a specific wavelength out of wavelength-division-multiplexed optical signals or adding an optical signal to be transmitted to the wavelength-division-multiplexed optical signals, comprising: a first optical circulator connected to a first optical fiber transmission line for transmitting optical signals in a first direction and a second optical fiber transmission line for transmitting optical signals in a second direction opposite to the first direction; a first multiplexer/demultiplexer connected to the first optical circulator, demultiplexing multiplexed optical signals received via the first optical fiber transmission line, and multiplexing optical signals having a plurality of different wavelengths; a first optical switch connected to the first multiplexer/demultiplexer, receiving demultiplexed optical signals having a first wavelength from the first multiplexer/demultiplexer, and outputting the demultiplexed optical signals having the first wavelength received from the first multiplexer/demultiplexer; a first add-drop port connected to the first optical switch; a first receiver for receiving the demultiplexed optical signals having the first wavelength upon the demultiplexed optical signals having the first wavelength being output from the first optical switch via the first add-drop port; a first transmitter for transmitting optical signals having the first wavelength to the first multiplexer/demultiplexer via the first add-drop port; a second optical circulator connected to a third optical fiber transmission line for transmitting optical signals in the first direction and a fourth optical fiber transmission line for transmitting optical signals in the second direction; a second multiplexer/demultiplexer connected to the second optical circulator, demultiplexing multiplexed optical signals received via the fourth optical fiber transmission line, and multiplexing optical signals having the plurality of different wavelengths; a second optical switch connected to the second multiplexer/demultiplexer and the first optical switch, receiving demultiplexed optical signals having the first wavelength from the second multiplexer/demultiplexer, and outputting the multiplexed optical signals having the first wavelength received from the second multiplexer/demultiplexer a second add-drop port connected to the second optical switch; a second receiver for receiving the demultiplexed optical signals having the first wavelength upon the demultiplexed optical signals having the first wavelength being output from the second optical switch via the second add-drop port; and a second transmitter for transmitting optical signals having the first wavelength to the second multiplexer/demultiplexer via the second add-drop port.