All-optical packet processing and contention resolution using O-CDMA and optical bistability

The application of optical code division multiple access (O-CDMA) to the realm of all-optical packet switching is studied. O-CDMA encoded headers could be decoded by tuned delay lines and used to make routing decisions. By encoding only the header with O-CDMA codes, the bandwidth requirement on the O-CDMA encoder and decoder is lessened. Using the inherent threshold capability of bistable optical elements and wavelength routing, decoding of the packet headers and subsequent routing can be done all optically. Contention resolution is one of the challenges facing an all optical packet switching network. A scheme to reduce dropped packets due to collisions is presented by using optical bistability, four wave mixing and Mach-Zehnder interferometer (MZI) based optical switch with a loop delay line. This scheme, however, is limited to resolving contention between fix-length packets in a synchronous network.