Patent ID: 7058302

Claim:
A reconfigurable frequency add and drop multiplexer, comprising: a demultiplexer having at least two input ports for receiving two wavelength division multiplexes having N channels, and at least N+2 output ports, for all values of i from 1 to N, the i th output port of said demultiplexer being adapted to receive the corresponding i th frequency of a first multiplex received at said first input port, and for any value of i from 3 to N+2, said i th output port of said demultiplexer being adapted to receive the (i−2) th frequency of the second multiplex received at said second input port, a multiplexer having at least N+1 input ports and at least two output ports, for any value of i from 1 to N, the i th input port of said multiplexer being adapted to forward the i th frequency to a first output port of said multiplexer, and for any value of i from 2 to N+1, an i th input port of said multiplexer being adapted to forward the (i−1) th frequency to a second output port of said multiplexer, and optical switches for selectively connecting any i th output port of said demultiplexer, for i from 3 to N, to one of the (i−1) th input port of said multiplexer, the i th input port of said multiplexer, and the (i+1) th input port of said multiplexer, the first and second output ports of said demultiplexer being each respectively connected to the first and second input ports and to the second and third input ports of said multiplexer, and the (N+1) th and (N+2) th output ports of said demultiplexer being each connected respectively to the Nth input ports and to the (N+1) th input port of said multiplexer.