editorial...

Hindawi Publishing CorporationInternational Journal of OpticsVolume 2012, Article ID 530648, 2 pagesdoi:10.1155/2012/530648

Editorial

Nonlinear Fibre-Based Photonic Technologies

Sonia Boscolo,1 Juan Diego Ania Castanon,2

Christophe Finot,3 and Miguel Gonzalez Herraez4

1 Institute of Photonic Technologies, School of Engineering and Applied Science, Aston University, Birmingham B4 7ET, UK2 Instituto de Optica, CSIC, Serrano 121, 28006 Madrid, Spain3 Laboratoire Interdisciplinaire Carnot de Bourgogne, Unite Mixte de Recherche CNRS 5209, 9 avenue Alain Savary,21078 Dijon, France

4 Departamento de Electronica, Universidad de Alcala de Henares, Alcala de Henares, 28871 Madrid, Spain

Correspondence should be addressed to Sonia Boscolo, [email protected]

Received 6 March 2012; Accepted 6 March 2012

Copyright © 2012 Sonia Boscolo et al. This is an open access article distributed under the Creative Commons Attribution License,which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

The field of photonics is one of the fastest growing researchareas in modern science, having a direct and almost immedi-ate impact on the development of new technologies in fieldsranging from telecommunications to the biosciences. Pho-tonics, effectively an interdisciplinary field at the interface ofphysics, material science, and engineering, is very stronglylinked to the field of nonlinear science. Though nonlinearphysics has a rather long history, beginning with the worksof Newton and Huygens, science and technologies of the19th and most of the 20th century have been dominated bylinear mathematical models and linear physical phenomena.Over the last decades, there has been growing recognitionof physical systems in which nonlinearity introduces a richvariety of fundamentally new properties that can never beobserved in linear models or implemented in linear devices.

From a practical standpoint, nonlinearity adds to thedifficulty of understanding and predicting the system proper-ties. However, with suitable design and control, it is possibleto master and exploit nonlinear physical interactions andprocesses to yield tremendous benefits. The understandingand mastering of nonlinear optical systems has the potentialto enable a new generation of engineering concepts.

Although silica exhibits much lower optical nonlinearitythan crystals of such materials as lithium niobate or betabarium borate, silica fibres can provide a comparativelyenormous interaction length (more than 1 km) and tightconfinement (less than 2 µm2 mode area), which offers thelong-recognized possibility of using optical fibres for non-linear interactions. In high-speed optical communicationssuch nonlinear effects generally degrade the integrity of

the transmitted signal, but the same effects can be usedto realize a variety of optical functions that have practicalapplications in the field of light-wave technology. Nonlin-ear processes that have been exploited in demonstrationsand applications include stimulated Brillouin and Ramanscattering, as well as aspects of the Kerr effect variouslycalled self-phase modulation, cross-phase modulation, four-photon (four-wave) mixing, cross-polarization modulation,and parametric gain. Important examples of establishedand new emerging nonlinear fibre-based photonic technolo-gies essentially relying on nonlinear phenomena includeall-optical signal processing and regeneration in ultrafasttelecommunications, optical gating, switching and frequencyconversion, optical waveform generation and pulse shap-ing, optical parametric amplification, Raman amplifiersand lasers, high-power pulsed and continuous-wave lasers,broadband and supercontinuum (SC) light sources, andother applications. This is the area which is addressed in thisspecial issue: the development of novel photonic approaches,techniques, systems, and devices exploiting nonlinear effectsin optical fibres.

The use of nonlinear photonic technologies for managingsignals in the all-optical domain has enabled applications insuch diverse areas as optical telecommunications, metrology,optical sensing, microwave engineering, image processing,and optical computing, to name a few. Advantages ofprocessing the information in the all-optical domain includethe large available bandwidth and the parallelism intrinsicto the optical approach, which translate into high process-ing speeds. Although photonic technologies already play

2 International Journal of Optics

an important role in the context of high-speed communica-tions networks, their scope is, at present, largely restrictedto the transport layer rather than being used for complexrouting, processing and switching tasks which are performedin the electronic domain after an optical to electricalconversion which is costly and reduces system speed andlatency. Today, electronic techniques of signal manipulationare advanced compared to all-optical processing deviceswhich are still at the research stage rather than undercommercial development. Hence, considerable knowledgestill has to be accumulated, and new methodologies needto be explored before a true breakthrough can be achievedin this field, allowing the range of functions and operationscurrently accomplished electronically to be performed inthe optical domain. Furthermore, by using optical ratherthan electronic processing, additional functionality may bepossible.

Several textbooks exist that cover various aspects ofnonlinear fibre-based optical technology. There are alsoseveral tutorial and invited papers devoted to the topic.The purpose of this special issue is to provide a flavor ofthe state-of-the-art, recent developments and trends in thefield from both theoretical and experimental perspectives.The issue comprises eight papers submitted by distinguishedresearchers and their colleagues in their respective fields, whowere invited to contribute with an overview of the latestadvances in their own research area.

J. Azana et al. review recent work on the design andfabrication of all-fibre (long-period grating-based) devicesfor optical pulse shaping, particularly picosecond and subpi-cosecond flat-top pulse generation, and their application innonlinear optical telecommunication data processing, par-ticularly switching (demultiplexing) of optical time-divisionmultiplexed data signals in fibre-optic telecommunicationlinks operating at bit rates up to 640 Gbit/s. S. Boscolo et al.review recent theoretical and experimental progress on theuse of fibre nonlinearities for the generation and shaping ofoptical pulses and the applications of advanced pulse shapesin all-optical signal processing, with a focus on ultrahighrepetition rate pulse sources, parabolic and triangular pulsegeneration, coherent SC sources, and applications such asoptical regeneration, linear distortion compensation, signalpostprocessing in optical communication systems, opticalsignal doubling, and frequency conversion. I. O. Zolotovskiiet al. report theoretical predictions of the generation of stableself-similar frequency-modulated optical pulses in a length-inhomogeneous fibre gain medium, which enables subpi-cosecond pulse amplification up to the nanojoule energies.O. Vanvincq et al. review recent theoretical and experimentalwork on manipulating the Raman gain-induced solitonself-frequency shift dynamics in special solid-core photonicband-gap fibres and its impact on SC generation, withthe results showing efficient tailoring of the SC spectralextension as well as strong noise reduction at the SC long-wavelength edge. K. Krupa et al. discuss nonlinear frequencyconversion based on Bragg-scattering four-wave mixingin highly nonlinear fibre using a novel cost-effective andpartially coherent pumping scheme, with the experimen-tal results demonstrating efficient and tunable conversion

despite the large bandwidth and statistical independence ofthe pumps. E. Shlizerman et al. use the method of properorthogonal decomposition (POD) to demonstrate that low-dimensional models generated by a POD analysis provide agood framework for characterizing the underlying dynamicsand bifurcation behavior in mode-locked laser systems,and determining the optimal working regime for the laser(maximal suppression of the multipulsing instability). A.Komarov et al. present results of their research on multipulseoperation of passive mode-locked fibre lasers, addressing inparticular the formation of bound steady states of interactingsolitons in the presence of different nonlinear loss shapingmechanisms, the possibility of information coding in solitontrains with various bounds between neighboring pulses,and the formation of bound-enhancing powerful solitonwings as a result of dispersive wave emission due to lumpednonlinear losses. Finally, L. K. Oxenløwe et al. review recentexperimental advances in nonlinear optical signal processingfor Ethernet applications, with a focus on 1.28 Tb/s datageneration and demultiplexing.

Aknowledgments

We would like to thank all the authors for their invaluablecontributions and original ideas, the reviewers for providingthorough evaluations of the submitted papers, and theEditorial Staff of the International Journal of Optics forsuggesting that we organize this special issue and for theirwork in coordinating the editorial process. It has been ourpleasure putting this special issue together, and we hope thatyou enjoy reading it.

Sonia BoscoloJuan Diego Ania Castanon

Christophe FinotMiguel Gonzalez Herraez

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