Simultaneous WDM signal detection realized by ultrafast field sampling.

This paper proposes a novel detection technique for wavelength-division multiplexing (WDM) signals that uses the ultrafast field sampling approach. The proposed technique simultaneously samples the total field of the WDM signal with no wavelength-demultiplexing; its electrical post-processing provides a filtering function in the digital domain. As a result, the individual fields of the WDM channels, including mutual phase relationship, can be jointly reconstructed. As a preliminary demonstration, the simultaneous monitoring of a WDM signal composed of two channels with independent polarization states, is successfully performed using a dual-channel field sampling system with polarization diversity. This demonstration can be expanded to the detection of a WDM signal with N-channels by using an N-channel field sampling system. It is also experimentally-verified that the reconstructed fields preserve the mutual phase relationship of the original fields. This 'field sensitive' WDM detection may open new possibilities for advanced WDM monitoring systems and even the electrical compensation of linear and/or non-linear inter-channel cross-talk in digital coherent detection systems.