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.