Capacity bounding of coherence multiplexed local area networks due to interferometric noise

Coherence multiplexing exploits the coherence properties of optical sources so that many users may be multiplexed onto a single physical channel giving a secure, asynchronous mode of transmission, free of central network control. In the paper, for the first time, the system performance limitations owing to the impact of interference from unwanted users is presented and the suitability of LED, single-mode Fabry-Perot laser and DFB sources are considered. It is concluded that the single-mode Fabry-Perot is preferred, offering readily achievable interferometer length tolerances and near complete RF rejection of interferometric noise at the receiver. However, interferometric noise still limits the network capacity: a linewidth of 1nm permits 17 users to be simultaneously offered a single video channel with a BER < 10(-9).