Electronic compensation of chromatic dispersion using a digital coherent receiver

Abstract

Digital signal processing (DSP) combined with a phase and polarization diverse coherent receiver is a promising technology for future optical networks. Not only can the DSP be used to remove the need for dynamic polarization control, but also it may be utilized to compensate for nonlinear and linear transmission impairments. In this paper we present results of a 42.8Gbit/s nonlinear transmission experiment, using polarization multiplexed QPSK data at 10.7GBaud, with 4 bits per symbol. The digital coherent receiver allows 107,424 ps/nm of chromatic dispersion to be compensated digitally after transmission over 6400km of standard single mode fiber.

Fiber transmission characteristics of phase only pulse and its dispersion compensation in high power regime

“…The DSP-based coherent detection fully recovers both the phase and the magnitude of the complex electrical field of the light signal, allowing compensation of linear impairments including chromatic dispersion and polarization-mode dispersion [1,2]. Although nonlinear impairments can be compensated using DSPs as long as they are deterministic [3], the perfect compensation of nonlinear impairments is difficult.…”

Robust Multilevel Coherent Optical Systems With Linear Processing at the Receiver

“…The integer parameter in (18) and the real parameter in (19) are design parameters that can be optimized for the phase noise at hand. The receiver robustness can be further increased by resorting to the approach, based on linear prediction and still working in a symbol-by-symbol fashion, described in [36].…”

“…The described symbol-by-symbol asynchronous detection strategies (17), (18), and (17)- (19) and the updating rule (20) can be equivalently expressed as a function of the information symbols . This is certainly possible, since the sequence is, after all, a function of the sequence .…”

“…In both figures, we considered the case of a FFE alone, and in this case its coefficients are adjusted every symbol time to follow the phase variations, and the cases when a PLL or the asynchronous strategy (17), (18) are employed. The PLL equivalent bandwidth and the value of for the asynchronous strategy (17), (18), have been optimized for every value of the lasers linewidth. As previously mentioned, the asynchronous strategy exhibits an impressive robustness and is immune from the occurrence of losses of lock which on the contrary affect the PLL.…”

DSP-based compensation of non-linear impairments in 100 Gb/s PolMux QPSK

“…This can be obtained by inverting H(ω) (if this is known), by using adaptive algorithms (e.g. decision-directed and CMA) [12] (if it is not), or -as generally is the case -by a combination of the two approaches (a static filter to compensate for an approximately known amount of chromatic dispersion, followed by an adaptive filter for the compensation of random PMD, as well as other residual CD and other linear distortions) [13]. 3.…”