Optical fiber bus protection network to multiplex sensors: experimental validation of self-diagnosis

The experimental demonstration of a resilient wavelength division multiplexed (WDM) fiber bus network to interconnect sensors is reported. The network recovers operation after failures and it performs 'self-diagnosis', the identification of the failed constituent(s) from the patterns of surviving end-toend connections at its operating wavelengths. We provide clear evidence for the channel arrivals predicted by theory. In doing so, we explore the potential for spurious signals caused by reflections from broken fiber ends. Appropriate precautionary measures, especially the imposition of electronic thresholds at the receivers, can greatly reduce the scope for false diagnoses. Software to predict the failure site within the network from the arriving channels at the receivers is also reported. We describe how to coordinate self-diagnosis with protection switching so as to reduce the momentary service interruption.