Patent ID: 6041152
Filing Date: 2000-03-21
Classification: H04J

Abstract:
In a multiple channel communications system including an optical fiber transmission line and at least two cascaded wavelength division multiplexing components at each end of the transmission line, the improvement wherein said at least two wavelength division multiplexing components at each end of the transmission line is coupled to the transmission line via combiners, at least one of said combiners at one end of the transmission line being arranged to multiplex groups of signals from said cascaded wavelength division multiplexing components, each said group forming a different set of channels, and at least one of said combiners at said second end of the transmission line being arranged to demultiplex said groups of different wavelength signals received over the transmission line from said cascaded wavelength division multiplexing components and distribute the demultiplexed groups to at least two of the cascaded wavelength division multiplexing components at said second end of the transmission line,wherein said combiners are bi-directional combiners, and at least one of said multiplexing components at each end of the transmission line is a cascaded multiple channel multiplexer, and at least one of said multiplexing components at each end of the transmission line is a cascaded multiple channel demultiplexer.wherein said cascaded multiple channel multiplexer comprises:a plurality of Mach-Zehnder interferometer units, each unit comprising a pair of 50/50 fiber optic couplers connected by a pair of Bragg gratings and three functional ports including two multi-channel input/output ports, and one single channel input port, said Bragg gratings being tuned to a wavelength of the single channel input port;means for connecting a plurality of transmitters respectively to said single channel input ports;means for connecting input/output ports of adjacent said interferometer units in a cascade configuration; anda common output port on a last of said cascaded interferometer units, said common output port of each multiplexer being connected to a different input port of one of the combiners.