Kerr nonlinearity imposes a limit on the achievable transmission performance and capacity of optical fibre communication links. We show that the nonlinear distortions of a pair of phase-conjugated ...twin waves are essentially anticorrelated, so cancellation of signal-to-signal nonlinear interactions can be achieved by coherently superimposing the twin waves at the end of the transmission line. We demonstrate that by applying this approach to fibre communication, nonlinear distortions can be reduced by >8.5 dB. In dispersive nonlinear transmission, the nonlinearity cancellation additionally requires a dispersion-symmetry condition that can be satisfied by appropriately predispersing the signals. By using these techniques we succeed in transmitting a 400 Gb s-1 superchannel over 12,800 km of fibre. We further show a connection between the nonlinearity cancellation and a nonlinear noise squeezing effect. The concept of using phase-conjugated twin waves to suppress nonlinear interactions may prove beneficial in other physical systems governed by the nonlinear Schrödinger equation.
Roadmap of optical communications Agrell, Erik; Karlsson, Magnus; Chraplyvy, A R ...
Journal of optics,
06/2016, Letnik:
18, Številka:
6
Journal Article
Recenzirano
Odprti dostop
Lightwave communications is a necessity for the information age. Optical links provide enormous bandwidth, and the optical fiber is the only medium that can meet the modern society's needs for ...transporting massive amounts of data over long distances. Applications range from global high-capacity networks, which constitute the backbone of the internet, to the massively parallel interconnects that provide data connectivity inside datacenters and supercomputers. Optical communications is a diverse and rapidly changing field, where experts in photonics, communications, electronics, and signal processing work side by side to meet the ever-increasing demands for higher capacity, lower cost, and lower energy consumption, while adapting the system design to novel services and technologies. Due to the interdisciplinary nature of this rich research field, Journal of Optics has invited 16 researchers, each a world-leading expert in their respective subfields, to contribute a section to this invited review article, summarizing their views on state-of-the-art and future developments in optical communications.
We study the techno-economics of submarine systems constrained by a fixed electrical power supply. We show significant cost savings for high-capacity submarine systems using massive space-division ...multiplexing (SDM), even without assuming any savings from SDM-specific subsystem integration. Systems with about 100 parallel optical paths, e.g., ~50 fiber pairs are shown to provide minimum cost/bit, operating at reduced spectral efficiencies and deep within the linear regime. While advanced nonlinearity-optimized fibers and digital nonlinearity compensation schemes provide little to no gain in such systems, SDM integration of amplifiers and transponders is shown to be a source for significant additional cost savings. We further examine the permissible cost premium for multicore fibers in such massively parallel systems and revisit various design tradeoffs for optical amplifiers, showing that a reduced noise figure can be traded for better power conversion efficiency. We also evaluate potential gains from increasing the available electrical supply power and discuss reliability aspects of massively parallel submarine systems.
We present fiber-nonlinearity-tolerant transmission of polarization-division multiplexed binary phase-shift keying (PDM-BPSK) through a nonlinear noise squeezing (NLNS) effect that is achieved by ...optimized digital electronic dispersion precompensation. With the improved nonlinear tolerance, a 406.6-Gb/s superchannel consisting of eight 37.5-GHz-spaced 32-Gbaud Nyquist-filtered PDM-BPSK signals is transmitted over a 12800-km (160 × 80-km) EDFA-only amplified dispersion-unmanaged nonzero-dispersion-shifted fiber link. We establish a connection between the beneficial NLNS effect and the recently reported phase-conjugated twin wave (PCTW) concept and further generalize the PCTW concept to vector twin waves that are traveling through a fiber link along orthogonal dimensions such as time and space. Moreover, we apply the PCTW concept to wavelength-division-multiplexed (WDM) superchannel transmission by treating the entire WDM superchannel as a twin wave to further mitigate interchannel nonlinear effects. Through numerical simulations, we show that the generalized PCTW technique can effectively mitigate interchannel nonlinear impairments, in addition to mitigating intrachannel nonlinear impairments.
The 25 years since the founding of the Journal of Lightwave Technology have seen more than three orders of magnitude increase in the capacity of optical transmission systems. This dramatic increase ...was brought about by the deployment of WDM and advances in high-speed transmission technologies.
Parametric amplifiers driven by two pump waves McKinstrie, C.J.; Radic, S.; Chraplyvy, A.R.
IEEE journal of selected topics in quantum electronics,
2002-May-June, 2002-05-00, 20020501, Letnik:
8, Številka:
3
Journal Article
Recenzirano
The theory of parametric amplifiers driven by two pump waves is developed. By choosing the pump wavelengths judiciously, one can design an amplifier that produces uniform exponential gain over a ...range of wavelengths that extends at least 30 nm on either side of the average pump wavelength.
Celebrating the 20
anniversary of Optics Express, this paper reviews the evolution of optical fiber communication systems, and through a look at the previous 20 years attempts to extrapolate ...fiber-optic technology needs and potential solution paths over the coming 20 years. Well aware that 20-year extrapolations are inherently associated with great uncertainties, we still hope that taking a significantly longer-term view than most texts in this field will provide the reader with a broader perspective and will encourage the much needed out-of-the-box thinking to solve the very significant technology scaling problems ahead of us. Focusing on the optical transport and switching layer, we cover aspects of large-scale spatial multiplexing, massive opto-electronic arrays and holistic optics-electronics-DSP integration, as well as optical node architectures for switching and multiplexing of spatial and spectral superchannels.
We describe the operation of a two-pump parametric optical regenerator. It is shown that higher order parametric coupling provides optical regeneration with a high extinction ratio. Excessive ...spectral broadening is studied in a two-pump architecture and compared with that of the one-pump parametric regenerator. We show that the spectral widths of the higher order terms can be controlled in amplifiers by using counterphased optical pumps.
We present a simple, silica waveguide optical equalizer that significantly mitigates intersymbol interference (ISI) impairments for many wavelength-division multiplexed (WDM) channels simultaneously. ...We study the mitigation of ISI arising from band-limited transmitters, narrow-band optical filtering, chromatic dispersion, and polarization-mode dispersion (PMD). We demonstrate significant improvements, both single- and multichannel, at 40 Gb/s with a single, potentially set-and-forget device.
We experimentally demonstrate nondegenerate four-wave mixing (FWM) between waves belonging to different spatial modes of a 5-km-long few-mode fiber (FMF). Of the three inter-modal FWM (IM-FWM) ...processes possible, two have been experimentally observed. These IM-FWM processes are found to be phase-matched over very large frequency separations of several Terahertz between the waves. In contrast to FWM in single-mode fibers that require operating near the zero-dispersion wavelength to achieve phase matching, IM-FWM in a FMF can be fully phase matched in the presence of large chromatic dispersion in each spatial mode.
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