Fiber-optic communication systems form the high-capacity transport infrastructure that enables global broadband data services and advanced Internet applications. The desire for higher per-fiber transport capacities and, at the same time, the drive for lower costs per end-to-end transmitted information bit has led to optically routed networks with high spectral efficiencies. Among other enabling technologies, advanced optical modulation formats have become key to the design of modern wavelength division multiplexed (WDM) fiber systems. In this paper, we review optical modulation formats in the broader context of optically routed WDM networks. We discuss the generation and detection of multigigabit/s intensity- and phase-modulated formats, and highlight their resilience to key impairments found in optical networking, such as optical amplifier noise, multipath interference, chromatic dispersion, polarization-mode dispersion, WDM crosstalk, concatenated optical filtering, and fiber nonlinearity

Advanced Optical Modulation Formats

Advanced optical modulation formats have become a key ingredient to the design of modern wavelength-division-multiplexed (WDM) optically routed networks. In this paper, we review the generation and detection of multigigabit/second intensity- and phase-modulated formats and highlight their resilience to key impairments found in optical networking, such as optical amplifier noise, chromatic dispersion, polarization-mode dispersion, WDM crosstalk, concatenated optical filtering, and fiber nonlinearity

Advanced Modulation Formats for High-Capacity Optical Transport Networks

Differential phase-shift keying (DPSK) has attracted significant attentions in research and development during the last several years. An overview of DPSK for high spectral efficiency optical transmission is presented in this paper. The advantages of DPSK in terms of receiver sensitivity and tolerance to fiber nonlinearity will be discussed in detail. A simplified method for estimating the performance of phase-shift keying in numerical simulations is explained. Results of experimental and numerical investigations of several phase shift keying formats, including polarization division multiplexing and multilevel encoding, will be reviewed. Finally, methods for further enhancing performance of phase-shift keying in long-haul transmissions, specifically the compensation of nonlinear phase jitter, are presented.

Differential phase-shift keying for high spectral efficiency optical transmissions

This paper reviews ultrahigh-speed data transmission in optical fibers based on optical time division multiplexing (OTDM) transmission technology. Optical signal processing in the transmitter and receiver as well as the requirements on ultrahigh-speed data transmission over a fiber link are discussed. Finally, results of several OTDM-transmission experiments, including 160-Gb/s transmission over 4320 km, 1.28-Tb/s transmission over 240 km, and 2.56-Tb/s transmission over 160-km fiber link, are described

Ultrahigh-Speed OTDM-Transmission Technology

Publisher Summary The pseudo–linear transmission is a method for the transmission of high-speed time-division multiplexed (TDM) signals where fast variations of each channel waveform with cumulative dispersion allows important averaging of the intrachannel effects of fiber nonlinearity. The pseudo–linear transmission involves complex optimization of modulation format, dispersion mapping, and nonlinearity. These transmissions occupy a space somewhere between dispersion-mapped linear transmission and nonlinear soliton transmission. The pseudo-linear regime of transmission is characterized by a rapid pulse broadening, which results in a dramatic reduction of the solitonic effect on each pulse. As a result, full dispersion compensation can be used in this regime. Extensive analysis of pseudo-linear transmission and reviews of the TDM transmission experiments at 40 and 160 Gb/s have been provided in the chapter. Two new forms of nonlinear interactions between rapidly dispersing pulses namely intrachannel cross–phase modulation (IXPM) and intrachannel four–wave mixing (IFWM) are also presented. These two intrachannel effects are the most important nonlinear interactions in pseudo-linear transmission and determine the dispersion mapping even for the wavelength–division multiplexed (WDM) systems. Further, the chapter describes the semiconductor–based technologies that enable the development of stable and reliable high–speed transmitters and receivers.

Pseudo-Linear Transmission of High-Speed TDM Signals: 40 and 160 Gb/s

A comparison of carrier-suppressed return-to-zero (CSRZ) and single sideband return-to-zero (SSB-RZ) formats is made in an attempt to find the optimum modulation format for high bit rate optical transmission systems Our results show that CSRZ is superior to return-to-zero (RZ) and SSB-RZ with respect to signal degradation due to Kerr nonlinearities and chromatic dispersion in wavelength division multiplexing (WDM) as well as in single-channel 40-Gb/s systems over standard single-mode fibers (SSMF) It is shown that CSRZ enables a maximum spectral efficiency of approximately 07 (b/s)/Hz in a N/spl times/40 Gb/s WDM system with equally polarized channels Furthermore, the CSRZ format in N/spl times/40 Gb/s WDM systems shows no further signal degradation compared to single-channel transmission

Alternative modulation formats in N/spl times/40 Gb/s WDM standard fiber RZ-transmission systems

We show that the alternate polarization of adjacent bits and channels in N/spl times/40-Gb/s wavelength-division-multiplexing (WDM) transmission system causes significant improvement of system performance through suppression of nonlinear effects. The suppression of nonlinear effects results in an improvement of the spectral efficiency in N/spl times/40-Gb/s WDM systems.

Improvement of system performance in N x 40-Gb/s WDM transmission using alternate polarizations

General guidelines for high-speed time-division multiplexing (TDM) data-rate transmission are essential for the increase of the overall transmission capacity. In this paper, general theoretical investigations concerning fiber chromatic dispersion in optical TDM systems are performed. Recent experiments that confirm the theoretical predictions are presented. Nonzero dispersion-shifted fiber and standard single-mode fiber are recommended for 40 and 160 Gb/s, respectively, independent of the chromatic dispersion compensation scheme.

Impact of fiber chromatic dispersion in high-speed TDM transmission systems

The influence of bitwise phase changes in 160 Gbit/s transmission systems is investigated. While high penalties are observed for constant phase, intrachannel four-wave mixing is optimally reduced by a phase alternating every bit between 0 and π/2 or every two bits by π.

https://ieeexplore.ieee.org/iel5/10668/33653/01601252.pdf

Influence of Bitwise Phase Changes on the Performance of 160 Gbit/s Transmission Systems

We investigate the impact of the prechirp on nonreturn-to-zero (NRZ)-based single-channel and 40-Gb/s/ch wavelength-division-multiplexing systems over standard single-mode fibers by means of numerical simulations. It was shown that prechirping of NRZ pulses improve the total transmission length and make the NRZ pulses more robust to Kerr-nonlinearities.

B. Konrad

Papers

Alternative modulation formats in N/spl times/40 Gb/s WDM standard fiber RZ-transmission systems

Improvement of system performance in N x 40-Gb/s WDM transmission using alternate polarizations

Impact of fiber chromatic dispersion in high-speed TDM transmission systems

Influence of Bitwise Phase Changes on the Performance of 160 Gbit/s Transmission Systems

Prechirp in NRZ-based 40-Gb/s single-channel and WDM transmission systems