ADVANCES IN OPTICAL AMPLIFIERS Edited by Paul Urquhart Advances in Optical Amplifiers Edited by Paul Urquhart Published by InTech Janeza Trdine 9, 51000 Rijeka, Croatia Copyright © 2011 InTech All chapters are Open Access articles distributed under the Creative Commons Non Commercial Share Alike Attribution 3.0 license, which permits to copy, distribute, transmit, and adapt the work in any medium, so long as the original work is properly cited. After this work has been published by InTech, authors have the right to republish it, in whole or part, in any publication of which they are the author, and to make other personal use of the work. Any republication, referencing or personal use of the work must explicitly identify the original source. Statements and opinions expressed in the chapters are these of the individual contributors and not necessarily those of the editors or publisher. No responsibility is accepted for the accuracy of information contained in the published articles. The publisher assumes no responsibility for any damage or injury to persons or property arising out of the use of any materials, instructions, methods or ideas contained in the book. Publishing Process Manager Ana Nikolic Technical Editor Teodora Smiljanic Cover Designer Martina Sirotic Image Copyright Katharina Wittfeld, 2010. Used under license from Shutterstock.com First published February, 2011 Printed in India A free online edition of this book is available at www.intechopen.com Additional hard copies can be obtained from orders@intechweb.org Advances in Optical Amplifiers, Edited by Paul Urquhart p. cm. ISBN 978-953-307-186-2 free online editions of InTech Books and Journals can be found at www.intechopen.com Part 1 Chapter 1 Chapter 2 Chapter 3 Part 2 Chapter 4 Chapter 5 Chapter 6 Preface IX Semiconductor Optical Amplifiers: General Concepts 1 Semiconductor Optical Amplifiers 3 M. Haridim, B.I. Lembrikov, Y. Ben-Ezra Semiconductor Optical Amplifier Nonlinearities and Their Applications for Next Generation of Optical Networks 27 Youssef Said and Houria Rezig A Frequency Domain Systems Theory Perspective for Semiconductor Optical Amplifier - Mach Zehnder Interferometer Circuitry in Routing and Signal Processing Applications 53 George T. Kanellos, Maria Spyropoulou, Konstantinos Vyrsokinos, Amalia Miliou and Nikos Pleros Semiconductor Optical Amplifiers: Wavelength Converters 79 Semiconductor Optical Amplifiers and their Application for All Optical Wavelength Conversion 81 Oded Raz The Application of Semiconductor Optical Amplifiers in All-Optical Wavelength Conversion and Radio Over Fiber Systems 105 Lin Chen, Jianjun Yu, Jia Lu, Hui Zhou and Fan Li Impact of Pump-Probe Time Delay on the Four Wave Mixing Conversion Efficiency in Semiconductor Optical Amplifiers 129 Narottam Das, Hitoshi Kawaguchi and Kamal Alameh Contents Contents VI Pattern Effect Mitigation Technique using Optical Filters for Semiconductor-Optical-Amplifier based Wavelength Conversion 147 Jin Wang Semiconductor Optical Amplifiers: Other Processing Functions 163 Chromatic Dispersion Monitoring Method Based on Semiconductor Optical Amplifier Spectral Shift Effect in 40 Gb/s Optical Communication Systems 165 Ming Chen Slow and Fast Light in Semiconductor Optical Amplifiers for Microwave Photonics Applications 179 Perrine Berger, Jérôme Bourderionnet, Daniel Dolfi, Fabien Bretenaker and Mehdi Alouini Photonic Integrated Semiconductor Optical Amplifier Switch Circuits 205 R. Stabile and K.A. Williams Negative Feedback Semiconductor Optical Amplifiers and All-Optical Triode 231 Yoshinobu Maeda Erbium-Doped Amplifiers and Lasers 253 Coherent Radiation Generation and Amplification in Erbium Doped Systems 255 Sterian Andreea Rodica Optical Amplifiers from Rare-Earth Co-Doped Glass Waveguides 279 G. Vijaya Prakash, S. Surendra Babu and A. Amarnath Reddy Tunable Fibre Lasers Based on Optical Amplifiers and an Opto-VLSI Processor 301 Feng Xiao, Kamal Alameh and Yong Tak Lee Equivalent Circuit Models for Optical Amplifiers 327 Jau-Ji Jou and Cheng-Kuang Liu Chapter 7 Part 3 Chapter 8 Chapter 9 Chapter 10 Chapter 11 Part 4 Chapter 12 Chapter 13 Chapter 14 Chapter 15 Contents VII Other Amplifier Mechanisms 349 Dual-Wavelength Pumped Dispersion-Compensating Fibre Raman Amplifiers 351 André Brückmann, Guido Boyen, Paul Urquhart, Amaia Legarrea Imízcoz, Nuria Miguel Zamora, Bruno Bristiel and Juan Mir Pieras Fiber-Bragg-Grating Based Optical Amplifiers 375 Shien-Kuei Liaw, Kuang-Yu Hsu, Kuei-Chu Hsu and Peng-Chun Peng Burst-mode Optical Amplifiers for Passive Optical Networks 405 Ken-Ichi Suzuki Cascaded Nonlinear Optical Mixing in a Noncollinear Optical Parametric Amplifier 423 Chao-Kuei Lee Part 5 Chapter 16 Chapter 17 Chapter 18 Chapter 19 Pref ac e Optical Amplifi ers and Their Applications in Networks Optical amplifi ers are essential elements in advanced fi bre-based telecommunications networks. They provide the means to counteract the losses caused by the fi bre trans- mission medium, the components placed in the propagation path and the power divi- sion at optical spli ers. Amplifi ers therefore facilitate the high global capacities, long transmission spans and multipoint-to-multipoint connectivity required for operation with growing data volumes. In their absence fi bre networks would need many more optical-electrical-optical (O-E-O) converters for the electronic repeating, retiming and reshaping of a enuated and noisy bit streams. The consequences would be transmis- sion at signifi cantly lower data rates, requiring numerous fi bres in each cable; more node buildings, o en in expensive city centre locations; larger equipment cabinets, occupying valuable fl oor space; increased total power consumption, with its associated environmental impact and, very importantly, higher operating costs to be passed on to the customer. For these reasons optical amplifi er technologies have been key enablers en route to ubiquitous information availability. All-optical amplifi cation has found application in all categories of fi bre network, whether they be single modulated wavelength or multi-channel operation through the use of wavelength division multiplexing (WDM). When incorporated in the tree topol- ogy of a passive optical network (PON) for fi bre to the home (FTTH), a single amplifi er module allows around one thousand customers to be served from one head end. Such “long reach PONs” off er considerable cost savings. Amplifi ers in metropolitan area networks tend to be housed within node buildings that are interconnected by WDM “self-healing” fi bre rings. They enable operation with increased inter-node spans and ensure that the channel powers are suffi cient for wave- length routeing at the nodes by optical add-drop multiplexers. Wide area terrestrial networks, which are ring or mesh topologies, range in scope from the interlinking of a few towns to major trans-continental trunk routes. Operation is commonly with sever- al dozen WDM channels, each at a data rate of 10 Gbit/s or above. Wavelength routeing, by optical cross-connects, is desirable but it is possible only if the signal powers and optical signal-to-noise ratios are maintained at high values throughout the transmis- sion path by re-amplifi cation at suitable locations. Owing to the demands of electrical power feeds, the amplifi ers for terrestrial operation preferably reside in node buildings but this is not always possible in larger networks and reliable external electrical power- ing is required. Innovations in remote optical pumping and distributed amplifi cation are promising in this context. X Preface A specialised but important application of optical amplifi ers is in “repeaterless” sub- sea transmission for festoon, island-to-mainland and island-to-island links with spans of up to a few hundred kilometres. Costly submerged repeaters and their associated electrical power supplies can o en be eliminated by using distributed amplifi cation and remote optical pumping and confi ning all discrete amplifi ers to the terminal buildings. The longest span optical telecommunications networks traverse the world’s oceans. Their amplifi ers are housed within repeaters, which are normally spaced every 40-60 km over total transmission distances of up to 10 000 km. The ocean-bed is not readily accessible and reliability is vital to minimise the number of expensive and time-con- suming repairs. Trans-oceanic systems are o en designed for twenty-fi ve year work- ing lives, indicating the faith that network operators now have in optical amplifi er technology. The applications described here easily justify the substantial investment in amplifi er research and development that has taken place over the past three decades. However, what is now particularly impressive is that it is not a complete list of uses. Other do- mains include the incorporation of amplifi cation in computer interconnects. These can range from fi bre-based local area networks (LANs) with star or ring topologies to serve a building or campus to multi-branched optical back-planes within supercomput- ers. Another growing fi eld is in bus, ring and star based fi bre networks for sensors of many types. The know-how developed for telecommunications engineering thus has numerous potential applications in, for example, the structural monitoring of build- ings, bridges and dams, site perimeter security, industrial process control, pollution detection, and human safety in the mining, aviation, nuclear power, oil extraction and chemical processing industries. The view presented so far is of the amplifi er as a gain element, in which a enuated input signals pass through an appropriate photonic medium to emerge with signifi - cantly enhanced powers. However, research, especially in semiconductor media, has concentrated on other amplifi er functionalities. When one or more high intensity sig- nals traverse a suitable semiconductor optical amplifi er (SOA) they experience various nonlinear eff ects. The most important are self- and cross-phase modulation, sum and diff erence frequency generation, four-wave mixing and cross-gain and cross-polarisa- tion modulation. These phenomena, o en in combination with advanced waveguide- based interferometers, provide alternative device possibilities. Examples include: (i) wavelength converters, (ii) all-optical logic elements, (iii) photonic space switches, (iv) optical regenerators to repeat, retime and re-shape corrupted optical bit streams, (v) time domain demultiplexers for very high data rate signals consisting of picosecond pulses and (vi) optical clock-recovery modules for use at the receiver to overcome high frequency ji er. To take one example, wavelength converters, which off er greatest potential in wide area and metropolitan terrestrial networks, allow a channel to be transferred to an- other carrier wavelength without O-E-O regeneration. This is a particularly desirable functionality in high capacity networks that must be reconfi gured by wavelength re- routeing. Wavelength converters enable economies on the total number of channels and they avoid contention, where two diff erent data streams with the same carrier [...]... in- line amplification in gigabit passive optical networks (GPON), and fast nonlinear all -optical signal processing Freude (2010) In particular, SOAs are among the most promising candidates for all -optical processing devices due to their high-speed capability, low switching energy, compactness, and optical integration compatibility Dong (2008) Hence, besides its use as an in- line optical amplifier, SOA... scattering processes have been used for amplification in fibres: stimulated Brillouin scattering (SBS) and stimulated Raman scattering (SRS) Brillouin amplification, which provides gain within a very narrow frequency band by contra-directional pumping, has found use in distributed optical sensing, signal processing for microwave photonics and laboratory demonstrations with more futuristic domains, such... which provide the TE-mode dominant optical gain, and light-hole (LH) bands, which provide the TM-mode dominant optical gain The difference in the confinement factors for TE and TM modes leads to different TE and TM signal gains 10 Advances in Optical Amplifiers The polarization sensitivity of MQW–SOAs can be significantly reduced when the active layer is strained, e.g by introduction of lattice mismatch... during strained-layer heteroepitaxy called the Stranski-Krastanow (SK) growth mode Ustinov (2003) Spontaneously growing QDs are said to be self-assembling SK growth has been investigated intensively for InAs on GaAs, InP on GaInP, and Ge on Si structures Ustinov (2003) The energy shift of the emitted light is determined by the size of QDs that can be adjusted within a certain range by changing the amount... amplification, where one fibre can simultaneously provide gain and chromatic dispersion compensation There are many reports of combining erbium and Raman amplifiers, especially for application in high capacity systems The nonlinear optical phenomenon of four wave mixing (FWM) occurs in WDM transmission in optical fibres when the propagating wavelengths are in the vicinity of the wavelength of zero dispersion The... switch By performing their function in the optical domain, wavelength converting semiconductor amplifiers can thus allow a marked reduction in the number of large racks of electronic equipment in node buildings, with an associated saving of floor space, energy consumption and cost The Main Amplifier Types A global overview of the main types of optical amplifier for telecommunications is presented in Fig 1 and... components on a single chip In order to distribute UWB signals via optical fibers, it is desirable to generate these signals directly in the optical domain The advantages of the all -optical methods are following: decreasing of interference between electrical devices, low loss and light weight of optical fibers Lin (2005), Yao (2007), Wang (2006) Typically, Gaussian waveforms are used in UWB communications... SOA of length L as the ratio between the output optical power Pout = P ( L) and Pin Agrawal (2002) Pout P ( L) G (ω ) = = (5) = exp ( gL) Pin P (0) The gain saturation regime is defined by the gain dependence on the optical power according to equation (1) It can be shown that for the large-signal amplification factor the following 6 Advances in Optical Amplifiers relationship prevails Agrawal (2002)... The optical gain of MQW is higher due to multiple QWs Further improvement of the SOA performance is achieved by introducing an outer cladding region of a higher energy gap compared to the MQW barrier layers The optical confinement factor of MQW SOAs increases approximately linearly with the number of QWs Many applications of SOA such as optical amplification, optical switching and signal processing require... propagating signal(s) In contrast, semiconductor amplifiers provide the population inversion necessary to establish gain by the direct injection of electrical current into the active region via attached electrodes Fig 1 The main types of optical amplifiers for telecommunications, in which the functions of semiconductor optical amplifiers are a sample of those available Fibre optical amplifiers are cylindrical . ADVANCES IN OPTICAL AMPLIFIERS Edited by Paul Urquhart Advances in Optical Amplifiers Edited by Paul Urquhart Published by InTech Janeza Trdine 9, 51000 Rijeka, Croatia Copyright © 2011 InTech All. February, 2011 Printed in India A free online edition of this book is available at www.intechopen.com Additional hard copies can be obtained from orders@intechweb.org Advances in Optical Amplifiers, . savings. Amplifi ers in metropolitan area networks tend to be housed within node buildings that are interconnected by WDM “self-healing” fi bre rings. They enable operation with increased inter-node