Multi-carrier transmitter for future access networks

The authors present a multi-carrier transmitter based on a gain switched laser employed in a next generation access network. The simple, robust and cost efficient direct modulation based comb generation technique offers closely spaced coherent channels. Each of the channels is imposed with 2.5 Gbaud data using QPSK and 16-QAM formats. The authors also present a performance comparison between the commonly used coherent detection scheme and a novel receiver architecture based on a pilot tone aided direct detection scheme. The simplified low cost receiver, enabled by the phase correlated optical comb tones, eases the requirement for an expensive local oscillator (tunable laser), reduces the need for digital signal processing and also greatly enhances the phase noise tolerance of the system.