Maurice O'Sullivan

Performance of Dual-Polarization QPSK for Optical Transport Systems

The emergence of capable semiconductor processes has allowed digital signal processing to extend the application range of high-capacity optical systems. We report the performance of polarization multiplexed (or dual-polarization) quadrature phase-shift keying at 40 and 100 Gb/s.

Electronic precompensation of optical nonlinearity

We introduce digital precompensation for optical nonlinearities. A 10-Gb/s transmitter subsystem is described. Experimental results, across 320 and 1280 km of standard single-mode fiber (G.652) without any optical compensators, show substantial elimination of self-phase modulation. Some of the limits of this method are explored.

5120 km RZ-DPSK transmission over G652 fiber at 10 Gb/s with no optical dispersion compensation

We report the longest unregenerated reach achieved for a 10 Gb/s return-to-zero differential phase shift keying (RZ-DPSK) system on standard dispersion fiber (G652) with no optical dispersion compensation.

Advances in High-Speed DACs, ADCs, and DSP for Optical Coherent Transceivers

We examine analog-to-digital and digital-to-analog converters (ADCs and DACs), as well as digital signal processing (DSP) functions for optical coherent modems.

Modulation instability and its impact in multispan optical amplified IMDD systems: theory and experiments

The nonlinear interaction between amplified spontaneous emission noise and copropagating signal in a dispersive optical fiber is investigated both theoretically and experimentally. A transfer matrix formulation is used to solve the nonlinear propagation equation. A continuous wave (CW) input optical signal format isolates the effect of modulation instability (MI) from the signal self-phase modulation. The change of the relative intensity noise (RIN) spectrum at an optical receiver caused by MI has been analyzed extensively in multispan optical amplified systems, and thus the impact of MI in the performance of intensity modulation and direct detection (IMDD) systems is evaluated. Performance of systems with distributed dispersion compensation (DC) and a lumped DC at the receiver are compared in terms of the effect of MI, the results show that the highest efficiency of DC to reduce the effect of MI can be achieved by putting a lumped DC module at the receiver side. Excellent agreement between theory and experiment demonstrates a good understanding of the mechanism of MI and its impact in the performance of terrestrial optical transmission systems.

WDM Performance and PMD Tolerance of a Coherent 40-Gbit/s Dual-Polarization QPSK Transceiver

We report the measured wavelength-division-multiplexing (WDM) performance and polarization-mode dispersion (PMD) tolerance of a coherent 40-Gbit/s dual-polarization quadrature phase shift keying (DP-QPSK) transceiver at 50-GHz minimum channel spacing in a 40-channel 40-span test bed comprised of 3200 km of uncompensated G.652 fiber. We also evaluate the impact of polarization-dependent loss (PDL) on system performance and present the measured tolerance to frequency misalignment between the transmitter and a multiplexer/demultiplexer filter pair.

5120-km RZ-DPSK transmission over G.652 fiber at 10 Gb/s without optical dispersion compensation

We report the longest unregenerated reach achieved for a 10-Gb/s return-to-zero differential phase-shift keying system on standard dispersion fiber (G.652) with no optical dispersion compensation. A total of 82.433 ns/nm of chromatic dispersion compensation was achieved.

Electrical domain compensation of optical dispersion [optical fibre communication applications]

Recent advances in the electrical equalization of optical systems are presented in the context of standard methods. We report 10 Gb/s transmission over 60,000 ps/nm of optical dispersion from 3840 km of NDSF (non-dispersion shifted fibre).

Electronic dispersion compensation

This study reveals that electronic dispersion compensation (EDC) allows migration of existing 2.5 Gbit/s metro and core networks to 10 Gbit/s without installation of DCF. This work also shows that EDC enables reduction in operating expenditures for optical networks, reduction in cost of optical networks, and improvements in optical link performance. Methods for terminal-based EDC at 10 Gbit/s are also discussed

Characterization of Real-Time PMD and Chromatic Dispersion Monitoring in a High-PMD 46-Gb/s Transmission System

We demonstrate performance monitoring based on the electronic compensation provided within a dual-polarization quadrature-phase-shift-keyed coherent receiver. Measurements were made over an 8 times 100-km system with distributed high polarization-mode-dispersion fiber. A laboratory demonstration of in-service monitoring was completed over a ten-day period.