Optical Code Division Multiple Access Systems in High-Speed Telecommunications

"BNS and University of Colorado at Boulder propose a novel spectral optical code division muliple access (OCDMA) system with bipolar coede capability for use in ultra-high-speed communication applications. A prototype one-dimensional spectral OCDMA systemwill by construted, and the feasibility of a two-dimensional (2-D) OCDMA system will be demonstrated using digital micromirror or liquid crystal spatial light modulators (SLMs). The proposed technology integrates muliple encoders for different users into acompact central unit, reducing overall system costs. The use of a 2-D array modulator enables parallel encoding for multiple users, with certain rows dedicated to each user. The advantage of the proposed system is that the spectral codes arereconfigurable. Each subscriber is able to communicate with all other subscribers. With its spectral bipolar code capability, the system can reject multiple access interference. The system can be made very compact even with large numbers of subscriberswhen large format 2-D SLMs are use. Due to its programmability and two-dimensional operation in the optical domain, the system is suitable for implementing optically transparent routings in an ultra-fast Asynchronous Transfer Mode (ATM) switch."