Importance

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Abstract

A branching unit is provided for directing individual wavelengths of a WDM optical communication signal among a transmitting terminal, a receiving terminal and a branch terminal. The branching unit includes first and second cross bar switches each having at least a first, second and third port such that in a first state the first cross bar directs an optical signal appearing on the first port to the second port and in a second state the first cross bar directs the optical signal from the first port to the third port. A reflective filter couples the third port of the first switch to the third port of the second switch. The reflective filter is configured to reflect a prescribed wavelength and to transmit therethrough all remaining wavelengths forming the WDM signal. An optical fiber couples the second port of the first switch to the second port of the second switch. First and second circulators are also provided, which each have an input, output and an intermediate port. The intermediate port of the first and second circulators are coupled to the first port of the first and second switches, respectively. The input port of the first circulator is adapted to receive the WDM signal from the transmitting terminal and the output port of the first circulator is adapted to receive the prescribed wavelength and transmit it to the branching terminal. The input port of the second circulator is adapted to receive the prescribed wavelength from the branching terminal and the output port of the first circulator is adapted to receive the WDM signal and transmit it to the receiving terminal.

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First Claim