Novel WDM-PON Architecture Based on a Spectrally Efficient IM-FSK Scheme Using DMLs and RSOAs

This paper proposes a wavelength-division-multiplexing passive optical network architecture with colorless user terminals based on the use of a different modulation scheme for each way of communication. Narrow-frequency-shift keying (FSK) modulation obtained by direct modulation of a distributed feedback laser has been used for the downstream channel, and intensity modulation has been used for the upstream channel. The performance of a link based on this scheme has been assessed, with particular emphasis on the description of the narrow-FSK modulation technique and its range of applicability in terms of bit rates and power levels. The operation of the architecture is demonstrated by simultaneously transmitting Ethernet frames at 1.25 Gb/s (gigabit Ethernet) in both the upstream and downstream channels. Error rates for downstream and upstream channels show excellent performance for distances up to 50 km.