Optical FMCW Radar for Monitoring of Passive Optical Networks

Abstract:
Monitoring of future optical access networks forms the basis of an efficient network management to guarantee reliability and to meet a certain quality of service. In next generation optical access networks a large number of long distant subscribers will be adressed. Standard monitoring techniques like Optical Time Domain Reflectometry will either reach their performance limits in these networks or are very costly. A cheap and easy alternative is monitoring networks by optical FMCW using cost efficient directly modulated laser sources. In this paper the principle of optical FMCW radar technique is discussed. The impact of nonlinearities in the optical input signal to the range resolution and accuracy is pointed out and a simple preprocessing method is performed to compensate for the chirp nonlinearities. To further enhance the measurement resolution a novel cost efficient optical FMCW scheme for long range and high resolution detection is presented.