Coherent Equalization and POLMUX-RZ-DQPSK for Robust 100-GE Transmission

111-Gb/s PolMux-Quadrature Duobinary for Robust and Bandwidth Efficient Transmission

“…To simulate the generation of an 111-Gb/s PolMux-RZ-QPSK signal, we modeled a Mach-Zehnder modulator (MZM) driven with a clock of 27.75 GHz for pulse carving with a 50% duty cycle, and two IQ-modulators in parallel to generate the QPSK signals for the two polarizations that will be multiplexed [1]. The PolMux-16QAM transmitter was modeled in a similar way to [5].…”

“…Therefore, for each polarization, four different electrical binary streams with data rates of 13.875-Gb/s each are required. To simulate the PolMux-QDB signal, a PolMux-QPSK modulator is used [1] and the four electrical binary data streams driving it at a data rate of 27.75 Gb/s are first duobinary encoded and afterwards passed through baseband electrical filters with bandwidth , where is the symbol rate. These narrowband filters function as delay and add components through the intersymbol interference they induce between adjacent bits, resulting in a three-level electrical signal.…”

“…Providing full access to the optical field (i.e., amplitude, phase, and polarization) in the electrical domain, coherent detection and digital signal processing have, therefore, enabled the detection of advanced optical modulation formats, made it easier to use polarization-multiplexing (PolMux) efficiently, and enabled the compensation of most linear optical impairments. Therefore, coherent detection and digital signal processing have triggered an intensive investigation for modulation formats that can achieve data rates of up to 100 Gb/s with high spectral efficiencies (SE) in order to catch up with the rapid increase in demand for transmission bandwidth [1]- [3].…”

Invited Article: Polarization diversity and modulation for high-speed optical communications: architectures and capacity

“…Despite the fact that polarization modulation or multiplexing for optical communication has been studied for more than 2 decades, 1-3 the real-field application is rather recent when dual-polarization coherent detection modulation format becomes the de facto transport standard for high-speed long-haul transmission at 100 Gb/s and beyond. 4,5 The reason for lack of progress in polarization multiplexed systems in the past is that they are either much more complicated or more expensive than single-polarization systems, or the overly sophisticated detection algorithms cannot be supported by the electronics then. The recent advances in electronic digital signal processing (DSP) is with no doubt the enabling technology responsible for the optical transport breakthrough in optical communication industry during the last decade.…”

Performance of Dual-Polarization QPSK for Optical Transport Systems

“…Chromatic dispersion can be inverted without penalty. The polarization transfer function of the optical link can be tracked allowing electronic domain compensation of PMD and polarization dependent loss (PDL) [4], [5]. This tracking also allows practical polarization multiplexed products [6].…”