Detection of a Single 40 Gb/s Polarization-Multiplexed QPSK Channel With a Real-Time Intradyne Receiver in the Presence of Multiple Coincident WDM Channels

We have characterized the performance of a single-ended intradyne receiver when multiple wavelength-division multiplexed (WDM) channels are incident. Detection of a single 40 Gb/s dual-polarization QPSK channel is achieved within a band of up to 17 WDM channels using a receiver with real-time digital signal processing and without optical demultiplexing. Measurements are presented of the performance in a back-to-back configuration as well as after transmission over 400 km of standard single-mode fiber. The dependence of the coincident channels' interference on various parameters, such as the net chromatic dispersion and the orientation of the coincident channels' polarization tributaries relative to the receiver polarizer, is explored. We also investigate using a single interfering channel with its power appropriately scaled to represent multiple interfering channels as an alternative configuration for evaluating receiver performance. The single-interferer approach has significant disadvantages including increased polarization sensitivity and different scaling of the interference term arising from the channel-channel beating compared to true multi-channel interference.