This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).
The objective of this research is to investigate phase-coherent, fiber optic multiple access communications for efficient, flexible, and secure local access networks. The proposed coherent diversity receiver cancels multiple access interference and speckle noise that arise when interfering signals mix in an optical detector. Such interference dominates multiple access performance, but the fully coherent receiver minimizes the bit error rate. The approach is to quantify, through modeling and experimentation, the loss of signal orthogonality due to optical component impairments and to devise a detector to jointly estimate each signal and interferer to minimize bit error rates and increase system capacity.
With respect to intellectual merit, this research seeks to develop a quantitative understanding of optical impairments that has the potential to lead to new high-performance and low-cost designs for integrated optical devices. Determining the minimum detectable signal permits increased network reach. Joint detection maximizes network capacity, which is limited by multiple access interference. Providing fully passive, coherent two-way network access without phase locked loops, super-fast diodes, or optical sources in the user nodes minimizes cost.
With respect to broader impacts, research outcomes have the potential to lead to efficient, low-cost delivery of a broad array of information services, tailoring resources to the needs of each subscriber. Diversity and outreach are supported by offering several urban high school science students and teachers six summer weeks of "hands-on" project experience. A laboratory course in digital fiber optic Communications emerging from this work blends research and education.
