www.elsolucionario.org Optical Fiber Communications Optical Fiber Communications Principles and Practice Third Edition JOHN M SENIOR This highly successful book, now in its third edition, has been extensively updated to include both new developments and improvements to technology and their utilization within the optical fiber global communications network The third edition, which contains an additional chapter and many new sections, is now structured into 15 chapters to facilitate a logical progression of the material, to enable both straightforward access to topics and provide an appropriate background and theoretical support Key features • An entirely new chapter on optical networks, incorporating wavelength routing and optical switching networks • A restructured chapter providing new material on optical amplifier technology, wavelength conversion and regeneration, and another focusing entirely on integrated optics and photonics • Many areas have been updated, including: low water peak and high performance single-mode fibers, photonic crystal fibers, coherent and particularly phase-modulated systems, and optical networking techniques • Inclusion of relevant up-to-date standardization developments • Mathematical fundamentals where appropriate • Increased number of worked examples, problems and new references Third Edition Professor John Senior is Pro Vice-Chancellor for Research and Dean of the Faculty of Engineering and Information Sciences at the University of Hertfordshire, UK This third edition of the book draws on his extensive experience of both teaching and research in this area CVR_SENI6812_03_SE_CVR.indd Cover image © INMAGINE www.pearson-books.com JOHN M SENIOR This new edition remains an extremely comprehensive introductory text with a practical orientation for undergraduate and postgraduate engineers and scientists It provides excellent coverage of all aspects of the technology and encompasses the new developments in the field Hence it continues to be of substantial benefit and assistance for practising engineers, technologists and scientists who need access to a wide-ranging and up-to-date reference to this continually expanding field Optical Fiber Communications Principles and Practice Third Edition JOHN M SENIOR 5/11/08 15:40:38 OPTF_A01.qxd 11/6/08 10:52 Page i Optical Fiber Communications OPTF_A01.qxd 11/6/08 10:52 Page ii We work with leading authors to develop the strongest educational materials in engineering, bringing cutting-edge thinking and best learning practice to a global market Under a range of well-known imprints, including Prentice Hall, we craft high quality print and electronic publications which help readers to understand and apply their content, whether studying or at work To find out more about the complete range of our publishing, please visit us on the World Wide Web at: www.pearsoned.co.uk OPTF_A01.qxd 11/6/08 10:52 Page iii www.elsolucionario.org Optical Fiber Communications Principles and Practice Third edition John M Senior assisted by M Yousif Jamro OPTF_A01.qxd 11/6/08 10:52 Page iv Pearson Education Limited Edinburgh Gate Harlow Essex CM20 2JE England and Associated Companies throughout the world Visit us on the World Wide Web at: www.pearsoned.co.uk First published 1985 Second edition 1992 Third edition published 2009 © Prentice Hall Europe 1985, 1992 © Pearson Education Limited 2009 The right of John M Senior to be identified as author of this work has been asserted by him in accordance with the Copyright, Designs and Patents Act 1988 All rights reserved No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without either the prior written permission of the publisher or a licence permitting restricted copying in the United Kingdom issued by the Copyright Licensing Agency Ltd, Saffron House, 6–10 Kirby Street, London EC1N 8TS All trademarks used herein are the property of their respective owners The use of any trademark in this text does not vest in the author or publisher any trademark ownership rights in such trademarks, nor does the use of such trademarks imply any affiliation with or endorsement of this book by such owners ISBN: 978-0-13-032681-2 British Library Cataloguing-in-Publication Data A catalogue record for this book is available from the British Library Library of Congress Cataloging-in-Publication Data Senior, John M., 1951– Optical fiber communications : principles and practice / John M Senior, assisted by M Yousif Jamro — 3rd ed p cm Includes bibliographical references and index ISBN-13: 978-0-13-032681-2 (alk paper) Optical communications Fiber optics I Jamro, M Yousif II Title TK5103.59.S46 2008 621.382′75—dc22 2008018133 10 12 11 10 09 08 Typeset in 10/12 Times by 35 Printed and bound by Ashford Colour Press Ltd, Gosport The publisher’s policy is to use paper manufactured from sustainable forests OPTF_A01.qxd 11/6/08 10:52 Page v To Judy and my mother Joan, and in memory of my father Ken OPTF_A01.qxd 11/6/08 10:52 Page vi www.elsolucionario.org OPTF_A01.qxd 11/6/08 10:52 Page vii Contents Preface Acknowledgements List of symbols and abbreviations Chapter 1: Introduction 1.1 1.2 1.3 Historical development The general system Advantages of optical fiber communication References Chapter 2: Optical fiber waveguides 2.1 2.2 2.3 2.4 2.5 Introduction Ray theory transmission 2.2.1 Total internal reflection 2.2.2 Acceptance angle 2.2.3 Numerical aperture 2.2.4 Skew rays Electromagnetic mode theory for optical propagation 2.3.1 Electromagnetic waves 2.3.2 Modes in a planar guide 2.3.3 Phase and group velocity 2.3.4 Phase shift with total internal reflection and the evanescent field 2.3.5 Goos–Haenchen shift Cylindrical fiber 2.4.1 Modes 2.4.2 Mode coupling 2.4.3 Step index fibers 2.4.4 Graded index fibers Single-mode fibers 2.5.1 Cutoff wavelength 2.5.2 Mode-field diameter and spot size 2.5.3 Effective refractive index xix xxiii xxxii 1 10 12 12 14 14 16 17 20 24 24 26 28 30 35 35 35 42 43 46 54 59 60 61 OPTF_A01.qxd 11/6/08 10:52 Page viii viii Contents 2.6 2.5.4 Group delay and mode delay factor 2.5.5 The Gaussian approximation 2.5.6 Equivalent step index methods Photonic crystal fibers 2.6.1 Index-guided microstructures 2.6.2 Photonic bandgap fibers Problems References Chapter 3: Transmission characteristics of optical fibers 3.1 3.2 3.3 Introduction Attenuation Material absorption losses in silica glass fibers 3.3.1 Intrinsic absorption 3.3.2 Extrinsic absorption 3.4 Linear scattering losses 3.4.1 Rayleigh scattering 3.4.2 Mie scattering 3.5 Nonlinear scattering losses 3.5.1 Stimulated Brillouin scattering 3.5.2 Stimulated Raman scattering 3.6 Fiber bend loss 3.7 Mid-infrared and far-infrared transmission 3.8 Dispersion 3.9 Chromatic dispersion 3.9.1 Material dispersion 3.9.2 Waveguide dispersion 3.10 Intermodal dispersion 3.10.1 Multimode step index fiber 3.10.2 Multimode graded index fiber 3.10.3 Modal noise 3.11 Overall fiber dispersion 3.11.1 Multimode fibers 3.11.2 Single-mode fibers 3.12 Dispersion-modified single-mode fibers 3.12.1 Dispersion-shifted fibers 3.12.2 Dispersion-flattened fibers 3.12.3 Nonzero-dispersion-shifted fibers 64 65 71 75 75 77 78 82 86 87 88 90 90 91 95 95 97 98 98 99 100 102 105 109 110 113 113 114 119 122 124 124 125 132 133 137 137 OPTF_Z02.qxd 9/23/09 10:57 AM Page 1062 1062 Index frequency division multiplexing (FDM) 702, 750 frequency domain measurement 923–6 frequency modulation of subcarrier 702, 754–6, 758–60 frequency shift keying 767, 825–35, 846–7 heterodyne detection 871–3 frequency translators 634–6 Fresnel reflection 219–20, 232, 233, 448, 953–4 fringes (interference) 927–8 full width half power (FWHP) points 425, 679 fused biconical taper (FBT) coupler 260–3 fusion splices 234–6 GaAlAs see AlGaAs GaAlAsSb/GaSb 326 GaAlSb/GaSb 326 GaAs 322, 326, 433–4, 456 adsorption coefficient 449 injection laser 328 LED 407, 435 MESFETs 531, 686 GaAs/AlGaAs 326, 335, 397 injection laser 331 LED 405–6, 408–9, 433–4 gain-bandwidth product 523–4 gain clamping 563–5 gain-guided laser 334–6 Gaussian approximation (single-mode fiber) 65–71, 230 for digital receiver 715–21 Gaussian distribution, single-mode step index fiber 60, 66–7 Gaussian noise 715 Gaussian probability density function 716 Gaussian pulse response 1052–3 Germanium (Ge) absorption 449 photodiodes 447, 459, 473–4, 522 gigabit Ethernet (GbE) 1028 gigabit PON (GPON) 641–3, 1019–20 transceiver 641–3 glass fiber laser 366–9 Goos–Haenchen shift 35 Gorden-Haus effect 158, 800–1 graded index fiber 46–54, 107–8, 119–22, 185–7, 296 caustic surfaces 48–9 intermodal dispersion 47, 119–22 mode cutoff 51 mode volume 53 normalized frequency 53 numerical aperture 48 optimum profile 120 parabolic profile 119–20 partially graded 187 propagation constant 51–2 Wertzel, Kramers, Brillouin (WKB) approximation 48–52 Griffith equation for fracture stress of a crack 196 Griffith theory for surface flaws in glass 195–6 GRIN-rod lens 254–6, 271, 273, 342–3, 364, 371 tapered 419 group delay 64–5, 110, 145 index 30 velocity 28–30, 110, 113 velocity delay 155–7 group-velocity dispersion 154 guard ring structure (APD) 472 guide see waveguide heavy metal oxide glass 103 helium–neon laser 303, 941 HEMT photoreceiver 638–9 HEMT preamplifier 535 heterodyne detection 833 amplitude shift keying 868–71 frequency shift keying 871–3 phase shift keying 873–4 heterodyne nonsynchronous detection 855–6 heterodyne synchronous detection 853–6 heterojunction bipolar transistor (HBT) 535 heterojunctions 323–5, 328 anisotype 323 double 323–4, 328, 330–1 isotype 323 heterostructure 323 see also heterojunctions hi-birefringence couplers 263 high birefringence fibers 147–51 high density bipolar (HDB) code 707 high performance receivers 534–42 holes 309–10 hollow core glass fiber 104 hollow-core optical fibers homodyne detection 832, 834, 856–9 amplitude shift keying 874–5 OPTF_Z02.qxd 9/23/09 10:57 AM Page 1063 www.elsolucionario.org Index phase shift keying 874–5 homojunction 323, 325, 328, 459 hybrid modes (HE, EH) 36–7 PIN-FET receiver 532–4 hybrid fiber coaxial (HFC) cable 1014 hybrid multiplexing 778 hydrogen absorption by optical fibers 200–1 impact ionization in APD 471–2 impurity semiconductor 297, 316 index-guided laser 336–9 index-guided microstructures 75–7 index matching fiber joint 225 light emitting diode 408 optical detector 911, 918 indirect bandgap 313–16 indium antimonide 650 indoor cables 208 induced grating autocorrelation 929–30 InGaAs/GaSb 325 InGaAsP/InP 325, 346, 460–1, 475, 483 APD 474–9 injection laser 638 LED 4, 423 p–i–n photodiode 459, 461 photodetectors 475–6, 486–7 phototransistor 486–7 injection efficiency 323 injection laser diode (ILD) 4, 296, 327 injection locked semiconductor laser 835 InP 475 InP/InGaAsP 326 insertion loss port coupler 261 star coupler 265–7 WDM coupler 269 inside vapor-phase oxidation (IVPO) 180 integrated external cavity laser 372–6 integrated laser modulator 646 integrated optics 607–10 devices 616–36 beam splitters 616–23 bistable optical devices (BOD) 648–55, 660 COBRA 617–18 directional couplers 616–23 filters 627–33 modulators 623–7 stepped delta $ reversal coupler 618 1063 switches 616–23 planar waveguide 532–7 intensity modulation analog 6, 435, 742 digital 6, 435, 702, 708 interference filters 260, 912 interference fringes 927–8 interference microscope 927–30 interferometric modulators 625–6 interferometric sensors 927–30 intermediate frequency 829 Intermodal dispersion 44, 45, 47, 113–24 graded index fiber 119–22 mode coupling 118–19 rms pulse broadening 116–17, 120–2 step index fibers 45, 113–19 internal photoemission 446 Internet Protocol (IP) 989–92 intersymbol interference (ISI) 105, 710, 726, 731–4 intradyne detection 859–60 intramodal dispersion see chromatic dispersion intrinsic semiconductor 297, 317 ion-implanted IO (I3O) technology 614–15 ionization coefficients, ratio of 472, 522 isoelectronic impurity 316 jitter 710 Johnson noise 491 joint losses 219–33 measurement 954 by misalignment 220–2 multimode fiber 222–30 single-mode fiber 230–3 joints 217–33 angular coupling efficiency 227–8 connectors 243–51 lateral coupling efficiency 223–4 signal distortion 232 splices 233–43 junction capacitance 486, 677 just-enough-time (JET) protocol 1006 just-in-time (JIT) protocol 1006 Kerr effects 154–5 kinks 356 label switching router (LSR) 1002 ladder coupler 267–8 Lambertian intensity distribution 401 OPTF_Z02.qxd 9/23/09 10:57 AM Page 1064 1064 Index Laplacian operator 25 laser 2, 4, 6, 294–383, 675–9 broadened transition 305 cavity 304–5 double-channel planar buried heterostructure (DCPBH) 338 dynamic single-mode (DSM) 342 far-infrared 378–83 fiber 366–9, 376–8 gain-curve 305 gain-guided 334–6 grating assisted codirectional coupler with sampled reflector (GCSR) 375–6 helium-neon 303, 941 injection see semiconductor integrated external cavity 372–6 mid-infrared 378–83 modes 306–7 multiquantum-well (MQW) 339 Nd:YAG 364–5 nonsemiconductor 302, 364–9 nonzero extinction ratio 679 operation of 297–308 oscillation 303–8 threshold-condition 307–8 threshold gain 307–8, 321 plano-convex waveguide 337 population inversion 302–3, 307, 317–18 quantum cascade 381–3 quantum-well 339 rib waveguide 337 ridge waveguide 336–7 ruby (crystal) 303 sampled grating distributed Bragg reflector (SG-DBR) 374–5 semiconductor 4, 6, 294–7, 318–23, 327–64, 675–9, 711–12 analog transmission 328 broad-area device 330–1 buried heterostructure 338, 362, 413 carrier confinement 323–5, 328, 331 characteristics 350–62 coherence 295, 299 continuous wave (CW) operation 328 coupling to fiber 362–4, 676, 710–11 current confinement 330–1 dark line defects 361 dark spot defects 361 distributed Bragg reflector 344–7 distributed feedback (DFB) 344–7, 355, 370 double heterojunction (DH) 323–4, 328, 330–1 drive circuits 686–90 dynamic response 354–5 efficiency 328–30 emission pattern 331 external power efficiency 330 far field intensity distribution 331 feedback control 687–90 frequency chirp 355–6 heterojunctions 323–5 homojunction device 323, 325, 328 kinks 335 light output against current characteristic 676 linearity 677 linewidth 369–78, 835–6 logic interface 686–7 materials 325–7 mode hopping 360–1 modes 306–7, 332–3 multimode 307, 331–2, 333 noise 356–60 nonlinearities 334–5, 677 operational limitations 676–9 output spectrum 332 partition noise 360 periodic structures 627–33 radiation confinement 323–5, 328, 331 relaxation oscillations (RO) 354 reliability 361–2 rise time 678 single-mode 296, 333–4 stripe geometry 330–2, 350–1, 355 temperature dependence 677 threshold current 321, 323–30 threshold current density 321, 328 threshold gain coefficient 321 single frequency 342–50 single-mode 333–4, 342–50 single quantum-well (SQW) 339 lasing 303, 307–8 from semiconductor 317–23 lateral offset fabrication 259 lattice constant see parameter OPTF_Z02.qxd 9/23/09 10:57 AM Page 1065 Index matching 325–6 parameter 325–6 leaky modes 40, 51, 53 LED see light emitting diode light emitting diode 4, 6, 295–6, 396–436, 540, 675 advantages 397 analog modulation 397, 422 characteristics 422–35 coupling (to fiber) 403–5 dark line effects 433–4 degradation 433–5 dome 407 double heterojunction (DH) 405–6, 408–9, 411–14 drawbacks 397 drive circuits 679–85 edge emitter 411–14, 421–4, 426–7 efficiency 398–406, 408, 420–2 injected carrier lifetime 430–1 light output against current characteristic 422–5 linearization schemes 684–5 linewidth 397, 425–7 longer wavelength operation 433–5 materials 397–8 modulation 435–6 modulation bandwidth 397, 428–35 nonlinearities 423, 676–7 operational limitations 676–9 output 422–7 output spectrum 425–7 planar 407 power 398–406 power coupled (into fiber) 408, 410, 710–11 quantum-dot 418–9 quantum efficiency (external) 400 quantum efficiency (internal) 399–401, 423 radiance 403–5 resonant-cavity (RC) 416–8, 425 rise time 678, 730–1, 749 speed of response 430–4 stripe geometry 411 structures 406–22 superluminescence 414–16 superluminescent (SLD) 423–5 surface emitter 407–11, 419–21, 423–7 surface emitter (Burrus type) 408–10 temperature dependence 427, 677–8 transmission factor 402 1065 line coding 707, 734–9 linear encoding 703 linear retardation (single-mode fiber) 141 linearly polarized (LP) modes 36–41, 54 linewidth (optical source) 296, 323, 327, 397, 425–7, 679 injection laser 369–78, 835–6 liquid phase (melting) techniques 171–5 liquid phase epitaxy (LPE) 460 Lithium niobate (LiNbO3) 613, 614, 616 Littrow mounted grating 270–1 local area networks (LANs) 247, 1023–31 protocols 1024–5, 1027 local oscillator power 840–3 logic emitter coupled (ECL) 682, 687 interface (receiver) 681–2, 686–7 transistor-transistor (TTL) 681–2 long external cavity lasers (LEC) 371, 836 long-haul optical networks 1007–11 loose buffer tubes 205, 208, 209–11 loose tube cable 210–11 loss-minimized fiber 188–9 losses see attenuation low birefringent fibers 147, 148 low-water peak fiber 4, 93–4 low-water peak nondispersion-shifted fiber 188 Mach–Zehnder interferometer 625, 635, 654, 847 macrobending 199 magneto-optic devices 613 magneto-optic effect 837, 840 Manchester (biphase) encoding 702, 735–6 material absorption losses glass 90–4 measurement 914–17 material dispersion 110–13 parameter 111–13, 128 rms pulse broadening 110–12 zero point (ZMD) 127–9, 132, 133 Maxwell’s equation 24, 31, 35, 66 MCVD technique 149, 150 mean (mean square value) of random variable 116 mean power feedback control (injection laser) 688 mechanical splices 233, 236–41 meridional rays 16–20, 36, 47, 114, 119–20 OPTF_Z02.qxd 9/23/09 10:57 AM Page 1066 www.elsolucionario.org 1066 Index MESFET (metal Schottky field effect transistor) 531, 533, 636, 637 mesh topology 971 metal-semiconductor-metal (MSM) photodetectors 489–93 sensitivity 491 tunable photodetectors 492–3 metropolitan area optical networks 1011–13 microbend type coupler 264 microbending 135 microbending loss 102, 199–200, 204 microcracks in fiber 195–7 microplasma in APD 471 mid-infrared lasers 387–1 mid-infrared photodiodes 482–4 mid-infrared transmission 102–5 mid-infrared wavelengths 366 Mie scattering losses 97 Miller capacitance in FET preamplifier 693 minority carrier lifetime injected 430–1 radiative 313, 315, 323 MISFET (metal integrated semiconductor field effect transistor) 637 mixer-rod coupler 265 modal birefringence see birefringence modal noise 122–4, 141 mode boundary 53 coupling 42–3, 118–19, 727–8, 906–7 in intermodal dispersion 118–19, 727–8 coupling length 907 dispersion see intermodal dispersion hopping (injection lasers) 360–1 mode filters 907–9 patterns 42 planar guide (concept of) 26–8 scrambler 907–9 stripper (cladding) 910–11 volume 45, 53 mode cutoff graded index fiber 51 step index fiber 40, 45 mode delay factor 64–5 mode-field diameter 943–6 mode number 28, 36, 51–3 mode partition noise 347, 360 modes cylindrical fiber 36–54 differential attenuation of 118 electric field distributions 28–30, 41 equilibrium distribution 907–9 exact (step index fiber) 36–8 guided 26–8, 38, 40–2, 49–51 hybrid (HE, EH) 36–7 laser 306–7, 332–3 leaky 40, 45, 51, 53 LED 295–6 linearly polarized (LP) 36–41, 123 radiation 40, 53 second-order 123 steady-state distribution 907 transverse electric (TE) 28, 31–41 transverse magnetic (TM) 28, 31–41 modified chemical vapor deposition (MCVD) 177, 180–1 modulation analog 6, 702, 739–60 direct detection (DD) 435 direct intensity (D-IM) 741–7 double sideband suppressed carrier (DSBSC) 752–4 intensity (IM) 436 pulse 758–60 pulse amplitude (PAM) 703–5, 758 pulse frequency (PFM) 758–60 pulse position (PPM) 758 pulse width (PWM) 758 subcarrier double sideband (DSB-IM) 752–4 subcarrier frequency (FM-IM) 754–6 subcarrier intensity 750–2 subcarrier phase (PM-IM) 756–8 digital 6, 703–8, 735 direct formats 713–15 index 742 modulation bandwidth, LED 397, 428–35 modulators, integrated optical 623–7 molecular beam epitaxy (MBE) 478 moments of random variable 116 monochromator 910 monomode fiber 44 see also single-mode fiber MOSFET 534 multicarrier systems 886–94 high capacity transmission 890–4 polarization multiplexing 889–90 multifiber cables for outside plant applications 208–10 OPTF_Z02.qxd 9/23/09 10:57 AM Page 1067 Index multigranular optical cross-connect (MG-OXC) 993, 995 multihop networks 978 multilayer interference filter 272 multilevel codes 735 multilevel frequency shift keying 847 multimode fibers graded index 46–54, 107–8, 119–22, 185–7, 190, 296 mode equilibrium 907 modes 36–41 step index 43–6, 107–8, 113–19, 124–5, 184–5, 190–1, 296 multimode interference (MMI) coupler 618–23, 644, 652–3 multimode laser 307, 331–2 multimode propagation effects (fiber) 906–7 multiple connectors 247–8 multiprotocol label switching (MPLS) 1002–4 in Ethernets 1031, 1033 multiplexing frequency division (FDM) 702, 750 optical time division (OTDM) 765–6 orthogonal frequency division (OFDM) 768–71 space division (SDM) 702 subcarrier 766–8 time division (TDM) 436, 702 wavelength division (WDM) 269–80, 702, 771–7 multiplication factor in APD 475–6, 482, 517–22, 721 multiport fiber couplers 256 multiquantum-well (MQQ) laser 339, 477–9 n–n heterojunction 323 n type semiconductor 334 nanophotonic devices 661–2 narrow linewidth lasers 369–78 Nd:YAG laser 367 near-field intensity distribution 930–2, 943–4 near travelling wave (NTW) amplifier 552 Neodymium laser 366–7 networks local area 247 optical see optical networks noise amplified spontaneous emission (ASE) 560–2, 577, 800–1 dark current 468–70, 491, 503, 504 1067 figure (amplifier) 513–15 generation-recombination 491 injection laser 356–60 Johnson 491 modal 122–4 mode partition 347, 360 polarization modal 123 quantization 704 quantum 504–5 analog transmission 508–10, 739–41 digital signalling 505–8, 723–5 injection laser 721–5 receiver 510–24, 739–40 APD 516–23, 721–5 p–i–n photodiode 469–70, 511–15 p–n photodiode 511–15 relative intensity (RIN) 358–9 shot 504, 508, 511–12, 723 sources in receiver 510 thermal 503, 512–13, 725, 743–5 noise equivalent power (NEP) 468–70 noise model for travelling wave optical amplifier 780 nonlinear encoding 704–5 nonlinear optical digital gate (NODG) 597 nonlinear optical loop mirrors (NOLM) 590–2 nonlinear optics 98–9 nonlinear phenomena 151–5 Kerr effects 154–5 scattering effects 151–3 nonradiative recombination 312, 314, 325 nonreturn-to-zero signalling (NRZ) 106–9, 157–8, 711–3, 793–4 nonzero-dispersion-shifted fiber 4, 137–40, 189–90 profiles 138, 139 nonzero extinction ratio 679 normalized film thickness 611 normalized frequency 40–2, 45, 53 normalized phase change coefficient 61 normalized propagation constant 40–2, 62, 64, 126 numerical aperture (NA) 17–20, 23, 39, 48, 115, 228–9, 230 definition 18 equilibrium mode distribution 907 graded index fiber 48, 938–9 measurement of 938–40 OPTF_Z02.qxd 9/23/09 10:57 AM Page 1068 1068 Index numerical aperture (continued) practical fibers 184–8, 190 Nyquist rate (sampling) 703 Open Systems Interconnection (OSI) reference model 985–7 in local area networks 1023–4 optical add/drop multiplexer (OADM) 277–8, 282, 974–5, 978–9, 1036–7 optical amplification 549–97 optical amplifiers 550–97 applications 778–86 optical attenuation meter 951–2 optical bandwidth 428–31 optical bistability 648–55 optical burst switching 969 networks for 1004–7 protocols 1006–7 optical chopper 910 optical circuit-switched networks 998–1000 optical circuit switching 968, 972 optical circulator 281–2, 957–8 optical code division multiplexing (OCDM) 777 optical computation 656–63 optical continuous wave reflectometer (OCWR) 947 optical cross-connect (OXC) 975–6, 978–9 optical demultiplexer 974–5 optical detection 298–9 optical detectors 444–93 avalanche photodiode (APD) 6, 7, 470–82, 721–5 capacitance 957 dark current 450, 459, 473–4 device types 446–7 germanium (Ge) 447, 459 heterodyne 833 homodyne 832, 834 mid-infrared 482–4 mushroom waveguide 460-2 noise equivalent power (NEP) 468–70 p–i–n photodiode 6, 457–62 p–n photodiode 6, 447–8, 456–7 photoconductive 489–93 phototransistors 485–8 quantum-dot (QD) 484–5 quantum efficiency 451, 460, 462, 473, 487 resonant cavity enhanced (RCE) 467–8 responsivity 451–5 separate absorption and multiplication (SAM) APD 475–8 silicon (Si) 449, 450 traveling-wave 465–7 unitraveling-wave (UTC) 466–7 optical emission semiconductors 319–27 spontaneous 298, 311–13, 321, 396, 407, 678 stimulated 311–13, 321, 396, 397–08, 407, 678 optical Ethernet 1028–33 connections 1029 protocols 1029–30 SDH/SONET in 1033 optical feedback technique 539 optical fiber advantages of 7–10 alignment 219–33 angular momentum barrier 40 attenuation 4, 8, 13, 87–102 bandwidth-length product 108, 184–91, 679 bend loss 100–2 bow tie 148, 149 buffer jacket 184–8, 190, 203–4, 207–8 cables 194–8 see also cables characteristics (practical) 183–94 cladding of 16, 34–5, 173, 181, 184–8, 190, 941–3 cleaving 233–4, 244 core of 173, 181, 943 crack velocity 199 critical radius of curvature 101–2 dispersion flattened 74, 133, 137 dispersion shifted 4, 74, 132, 133–6 drawing see fiber, drawing end preparation 233–4 far-field intensity distribution 909, 938–40 fracture stress 195–8 Fresnel reflection 219–20 graded index 107–8, 119–22, 185–7, 296 see also graded index fiber hydrogen absorption 200–1 impulse response 697 joint losses 219–33 see also joint losses joints 217–33 losses 184–91 see also attenuation OPTF_Z02.qxd 9/23/09 10:57 AM Page 1069 www.elsolucionario.org Index low-water-peak 93–4, 188 measurements 905–58 mechanical properties of 195–8 microbending 102, 199–200 misalignment 220–2 multicomponent glass 171, 175, 184–5 multimode, cutoff wavelength measurements 934–8 near-field intensity distribution 930–2 PANDA 148, 149 perflourintated plastic 192–4 photonic bandgap 77–8 photonic crystal 75–8 plastic 191–4 plastic clad 190–1 polarization 140–51 polarization maintaining 839–40 polarization state 836–40 polymethyl methacrylate (PMMA) 191–3 preform 172, 177–81 preparation 170–83 proof testing 198 ray model 14–23, 26, 43–7, 47–8, 113–19 requirements of 170 scattering losses 95–9 signal distortion at joint 232 silica rich glass 175–6, 180–3 single-mode 44–5, 187–90, 296 sizes 184–8, 190 splices 233–43 spun 149 stability of transmission characteristics 199–203 step index multimode 43–6, 107–8, 113–19, 124–5, 184–5, 190–1, 296 single-mode 44–5, 55–6, 58–9, 107–8, 187–90, 296 strength and durability 195–8 stress corrosion 197–8 structure 12–13 theoretical cohesive strength 195 transmission characteristics 199–203 transmission cohesive strength 195 transmission loss factor (transmissivity) 95 triangular profile 466 types currently available 183–94 W 57, 136, 137 1069 optical fiber systems 5–7, 673–801 analog 6, 739–60 block schematic (intensity modulation) 742 direct intensity modulation (D–IM) 741–7 optical power budgeting 748–9 pulse techniques 758–60 quantum noise limit 745–6 rise time budgeting 749, 759 signal to noise ratio 739–40 subcarrier double sideband modulation (DSB–IM) 752–4 subcarrier frequency modulation (FM–IM) 754–6 subcarrier intensity modulation (PM–IM) 750–2 subcarrier phase modulation (PM–IM) 756–8 system planning 748–50 thermal noise limit 746 coherent see coherent optical fiber systems design considerations 700–3 digital 6, 703–39 bit error rate (BER) 710, 720–5 coding 104–5, 702, 734–6 dispersion-equalization penalty 731–4 error monitoring 709–11, 726 error probability 716–21 eye pattern 710 information capacity 734–5 intersymbol interface (ISI) 697, 710 pulse code modulation 702, 703–11 redundancy 734–6 regenerative repeater 708–11 safety margin 731–4 synchronization 706, 735 timing 706 digital planning considerations 708–39 channel losses 725–6 line coding 734–6 optical power budgeting 731–4 receiver 715–25 rise time 726–31 signal to noise ratio 721–2 temporal response 726–31 transmitter 711–15 in Europe 705–6, 708 fault location 952–8 in Japan 707, 708 modulation choice 702–3 OPTF_Z02.qxd 9/23/09 10:57 AM Page 1070 1070 Index optical fiber systems (continued) networks see networks in North America 707, 708 repeater 5, 700, 708–11, 731–2 optical isolators 280–1 optical micro-electromechanical system (OMEMS) 622–3 optical mixer 829 optical multiplexer 974–5 optical multiplexing section (OMS) 988 optical networks 967–9 access networks 1013–23 architecture 971–2 asynchronous transfer mode 985 burst-switched 1004–7 circuit-switched 998–1000 concepts 969–79 deployment of 1007–28 long-haul networks 1008–11 metropolitan area networks 1011–13 evolution of 967–8 internet protocol 989–92 local area networks 1023–8 modes 972 modularity 973 network routing 973 node and switching elements 974–6 Open Systems Interconnection (OSI) reference model 985–7 optical Ethernet 1028–33 optical transport network 987–9 packet-switched 1000–2 protected network 1027 protection 1034–8 scalability 974 structure 970 survivability 1034 switching modes 972–3 synchronous networks 980–4 terminology 970–4 topology 971 virtual circuits 973 optical node 974 optical orthogonal frequency division multiplexing (OOFDM) 770–1, 893–4 optical packet switching 968, 969, 972 optical parametric amplifiers 578–81 optical physical section (OPS) 988 optical power meters 948–9 optical regeneration 595–7 optical replication technology 640–2 optical return loss 946–7 optical router 974 optical signal to noise ratio 719–20 optical sources generations of 295 laser 2, 294–383, 676–9 light emitting diode 4, 6, 295–6, 325, 396–436 nonsemiconductor 364–9 semiconductor 4, 6, 294–7, 318–23, 327–64, 676–9 limitations 676–9 see also specific types optical time division multiplexing (OTDM) 765–6 optical time domain reflectometry (OTDR) 952–8 optical transistor (transphasor) 653 optical transmission section (OTS) 989 optical transmitter 711–15 optical transport network (OTN) 987–9 optimum profile (graded index fiber) 120–2 optoelectronic integration 636–43 orthogonal frequency division multiplexing (OFDM) 768–71 outside vapor-phase deposition (OVD) 176–8 outside vapor phase oxidation (OVPO) 176–8, 183 outside vapor-phase oxidation (OVPO) 176, 178, 183 overall dispersion in single-mode fibers 125–32 oxide isolation 331 p–i–n photodetector 540 p–i–n photodiode 6, 480, 534–5, 540, 541 operation of 457–8 speed of response 462–5 structures 457–62 p–n heterojunction 323, 475–6 p–n junction 309–11, 327, 334, 414–16, 460 p–n photodiode 6, 460 p–p heterojunction 323, 405–6 p type semiconductor 310–11, 334 packet 972, 973 wave 29 parabolic profile fiber 46–8, 52, 119–20 parabolic refractive index profile 69 paraxial ray equation 254 partial response (PR) coding 713–4 OPTF_Z02.qxd 9/23/09 10:57 AM Page 1071 Index passive optical network (PON) 641, 1016–23, 1031 long-reach 1022–3 peak detection feedback control for ADP 696 permeability 25 permittivity 25 Peterman II definition (MFD for single-mode fiber) 61 phase diversity reception 860–3 phase index 61 phase locked loop techniques 852 phase propagation constant 61, 62 phase sensitive detection 910–13, 930–2 phase shift keying 767, 825–35, 847–50 heterodyne detection 873–4 phase shift on reflection 27, 30–5 phase velocity 25, 28–30 phased-array structures 647 phased amplitude shift signaling (PASS) codes 736 phonon 98, 102, 313 photoconductive detectors 489–93 photoconductive gain 490 photoconductors 6, 489–93 photocurrent 451–5 photodetectors see optical detectors and photodiodes photodiodes avalanche operation 471–2 capacitance 462–3 cutoff (long wavelength) 455–6 dark current 450, 459 depletion layer (region) 447–8, 456–68 depletion width 456 detection principles 298–9, 447–8 diffusion of carriers 462 drift of carriers 462 Germanium (Ge) 449, 450, 473–4 with internal gain 470–82 mid-infrared 482–4 p–i–n structure 457–62, 462–3 quantum efficiency 451, 473 responsivity 451–5 sensitivity 447 Silicon (Si) 449, 450, 472–3 time constant 462–3 without internal gain 456–70 see also optical detectors photon 297, 298 photonic bandgap fibers 77–8 1071 photonic bandgaps photonic crystal fibers 14, 75–8 index-guided microstructures 75–7 photonic bandgap fibers 77–8 photonic integrated circuits 643–8 photorefractive effect 929–30 phototransistor 4, 6, 485–8 PIN–FET receiver 841 hybrid receiver 532–4 optimization 535–6 planar LED 407 planar waveguide 26–35, 610–15 field relations 1051–2 integrated optics 532–7 slab 610–11, 613 strip 613–14 Planck’s constant 297, 359 plano-convex GRIN-rod lens 422 plano-convex waveguide (PCW) laser 337 plasma-activated chemical vapour deposition (PCVD) 177, 181–2, 183 plastic-clad fibers 190–1 plastic fibers 191–4 points-of-presence (POP) in networks 1013–14 Polarization beam combiner (PBC) 892 Polarization beam splitter (PBS) 863, 891 polarization crosstalk 149, 150 polarization diversity reception 863 polarization in single-mode fiber 54, 140–51 polarization maintaining fibers 147–51, 827, 839–40 polarization modal noise 123 polarization mode dispersion 144–7, 957–8 polarization multiplexing 864, 889–90 polarization noise 957 polarization optical time domain reflectometer (POTDR) 957–8 polarization scrambler 957 polarization scrambling 863–4 polarization shift keying (PolSK) 829, 850–1 polarization state 634, 836–40 polarization-state control 837–40 polarization transformers 634–6 polymethyl methacrylate fabricated fiber 191 population inversion 302–3, 307, 317–18 semiconductors 317–18 port couplers 259 power law refractive index profile 127 power meters (optical) 948–9 OPTF_Z02.qxd 9/23/09 10:57 AM Page 1072 www.elsolucionario.org 1072 Index preform (fiber) 171, 177–81 probability density function (PDF) 716 profile dispersion 121–2, 127 profile parameter (graded index fibers) 6–48 proof testing of fiber 198 propagation constant 25, 36–42, 51–2, 61, 62, 70, 125, 141 normalized 40–2 vacuum 26 propagation vector for wave 25 proton bombardment 331 public telecommunications networks 978–9 PuEuTe/PbTe DH laser 380 pulse amplitude modulation (PAM) 703–5, 758 pulse broadening 105–32 in polarization mode dispersion 144–7 rms 109–13, 117–18, 120–2 temporal moments 116 variance 112, 116 pulse code modulation (PCM) 702, 703–11 30 channel system 706 pulse delay from material dispersion 110 pulse dispersion 125–32, 920–3 pulse frequency modulation (PFM) 758–60 pulse position modulation (PM) 758 pulse width (rms) 105–6 pulse width modulation (PWM) 758 pumping (laser) 303 Q-factor 738–9 quadrature amplitude modulation (QAM) 770–1, 849–50, 884–5 quadruple clad (QC) fiber 137 quantifation 704 quantum-cascade laser 381–3 quantum computation 663 quantum-dot laser 339–41 quantum-dot LEDs 416–19 quantum-dot photodetectors 484–5 quantum-dots 565–7 quantum efficiency injection laser 315, 323, 328–30 LED 399–400, 407 photodiode 451, 460, 462, 473 phototransistor 487 quantum limit to detection 723–5, 745–6 quantum noise 723–5, 739–40 analog transmission 739–40 digital signalling 723–5 quantum theory 297 quantum-well laser 339, 355 quaternary semiconductor alloys 326 radiance 403–5 radiation modes 40, 53 radiation-resistant fibers 201–3 radiative recombination 311–12, 315–16 radius of the fundamental mode 67 raised cosine (pulse shape) 722 Raman fiber amplifier 551, 571–5, 785–6 Raman–Nath regime 626 Raman scattering 99, 152–3, 551 rare earth doped fiber amplifiers 568–71 ray model 14–23, 26, 43–6, 47–8, 113–19 Rayleigh scattering losses 95–7, 102, 103, 143, 952, 954 rays meridional 16–20, 36, 47, 114, 119,121 skew 20–3, 36, 48 reach through avalanche photodiode (RAPD) 472–3 receiver 690–700 analog 741–7, 751–60 automatic gain control (AGC) 694–6 avalanche photodiode 516–23, 721–5 block schematic 690 capacitance 515–16 digital 715–25 dynamic range 694 equalization 691, 694, 697–700, 709 excess avalanche noise factor 522–3 gain-bandwidth product 523-4 high impedance front end 526, 692–4 high performance 534–42 linear channel 691 low impedance front end 525–6, 692 main amplifier 691, 696 noise 510–24, 721–5, 739–40 see also noise, receiver PIN–FET 841 preamplifier circuits 691–4 sensitivity 731–4, 824, 868–86 comparison of 877–86 structures 524–30 transimpedance front end 526–30, 694–5 recombination (carrier) 311–13, 312–16, 318 reconfigurable optical add/drop multiplexer (ROADM) 277–8, 282, 975, 1013 OPTF_Z02.qxd 9/23/09 10:57 AM Page 1073 Index redundancy in digital transmission 707, 734–6 Reed-Solomon codes 737–8 reference test methods (RTMs) 906, 911, 934–7 reflectance 946–7 reflection coefficient 32–3 refracted near field method (RNF) 923–2 refraction 14 refractive index definition 14 profile 44, 46, 121, 184–8, 190, 229 profile measurement 926–33 regenerative baseband recovery (PFM) 759 regenerator circuit 708–9 relative dispersion slope (RDS) 790–1 relative intensity noise (RIN) 358–9 relative refractive index difference 18, 39, 46, 115, 117, 227 relaxation oscillation (ROs) 354 repeater 5, 700 analog 709 regenerative (digital) 595–7, 708–11 spacing 711, 726 reserve-a-fixed duration (RFD) scheme 1007 reserve-a-limited duration (RLD) scheme 1007 resonant cavity LEDs 416–19 responsivity (optical detector) 451–5 return-to-zero (RZ), signalling 106–7, 711–3, 793–4 rib waveguide laser 337 ribbon fiber cable 210, 242 ridge waveguide laser 336–7 RIN value 358–9 ring network topology 971 wavelength assignment in 997 rise time APD 749 injection laser 678 LED 678, 730–1, 749 p–i–n photodiode 457–62, 726–31 rms impulse response graded index fiber (multimode) 120–1 step index fiber (multimode) 117–18 rms pulse broadening intermodal dispersion 116–17, 120–2 intramodal 121, 124–5 material dispersion 110–13 total 124–5, 126 1073 routing and wavelength assignment (RWA) 996–8 Sagnac interferometer 369 sampling (of analog signal) 703 scalar wave equation 66–9 scattering Brillouin 98–9, 551, 844 linear 95–7 Raman 551, 844 scattering effects 151–3 scattering losses 100–2 measurement 917–19 Mie 97 minimization of 103 nonlinear 98–9 Raman 99 Rayleigh 95–7, 102, 103, 143, 952, 954 scrambler (mode) 907–9 self-electro-optic effect device (SEED) 650–1, 661 self phase modulation 154, 155 SELFOC, GRIN-rod lens 256 semiconductor alloys (III–V) 325–6 APD 6, 7, 957 see also avalanche photodiode injection laser 4, 6, 7, 294–7, 318–23, 327–64 see also laser semiconductor injection laser diode (ILD) see also laser, semiconductor LED 6, 295–6, 396, 436 see also light emitting diode n type 310, 311 p–i–n photodiode 6, 457–62 p–n photodiode 6, 456–7 p type 310, 311 phototransistor 4, semiconductor optical amplifier (SOA) 552–67 gain clamping 563–5 performance 559–63 quantum-dot 565–7 theory 554–63 semitransparent mirror fabrication 259 shift keying 767 amplitude 825–35, 845 frequency 825–35, 846–7 phase shift 825–35, 847–50 short and coupled cavity laser 342–9 OPTF_Z02.qxd 9/23/09 10:57 AM Page 1074 1074 Index shot noise 833 signal to noise ratio (SNR) at receiver 105, 824 signals analog 703, 741, 750–8 digital 106–7, 703–8 silicon grating 270 silicon junction FET (JFET) 534 single frequency laser 342–50 single-hop networks 977–8 single-mode fiber 54–74 advantages 58 bend losses 101 cross-section 55–6 cutoff wavelength 54, 59–60, 73, 101 depressed cladding (DC) 58 dispersion flattened 137 dispersion management in 787 dispersion modified 132–40 dispersion optimization 59 dispersion shifted 133–6 effective refractive index 61–3 equivalent step index (ESI) 71–4 Gaussian approximation 65–71 graded index 55–6, 187–90 holey 5, 75–8 joint losses 230–3, 232 matched-cladding (MC) 58 material dispersion parameter 126 mode-field diameter (MFD) 59, 60–1, 60–2, 134, 135 mode-field radius 60 overall dispersion 125–32 polarization 54 propagation constant 61, 62, 70, 113 rotary splice 240–1 spot size 60–1 step index 43–6, 55–6, 58–9, 107–8, 187–90, 296 single-mode laser nonsemiconductor 364–9 semiconductor 296, 333–4 structures 333–4 single quantum-well (SQW) laser 339 skew rays 20–3, 36, 48 Snell’s law 14, 18, 22 soliton interaction 794–5 soliton propagation 155–8 soliton systems 792–801 sources see optical sources space division multiplexing (SDM) 703 spatial light modulator 659 speckle patterns 122–3 spectral slicing 774–6 spectral width see linewidth spectrum electromagnetic extrinsic absorption in silica 91–4 LED (output) 425–7 speed of response LED 430–4 photodiode 462–5 splices 135, 233–43 splitting loss (star coupler) 265–7 spontaneous emission 298, 311–13, 321, 370, 396, 407 spontaneous emission factor 370 spontaneous lifetime 300 spot size 67, 69, 230, 937–8 Springroove® splice 239 standard single-mode fiber 187–8 star coupler 257, 259, 264–8 network 760–4 star couplers 976 star topology 971 statistical multiplexing 972 step index fiber mode cutoff 40, 45 modes 36–41 multimode 43–6, 107–8, 113–19, 124–5, 184–5, 190–1 intermodal dispersion 45, 47, 113–24 mode volume 45 rms impulse response 117–18 propagation constant 36–42 single-mode 43–6, 107–8, 187–90, 296 see also single-mode fiber stimulated Brillouin scattering (SBS) 98, 844 stimulated emission 297–9, 317–23 stimulated Raman scattering (SRS) 99, 844 Stokes component 152 stress corrosion of fiber 197–8 stripe geometry 333 stripper (cladding mode) 910–11 subcarrier multiplexing 766–8 surface acoustic wave (SAW) 626 surface-emitting LED (Burrus type) 407–11 switch delay feedback control (injection laser) 354–5, 678 switches (integrated optic) 616–23 OPTF_Z02.qxd 9/23/09 10:57 AM Page 1075 www.elsolucionario.org Index synchronous digital hierarchy (SDH) 981, 984 synchronous optical network (SONET) 584, 980–4 tapered fiber lenses 419 TE–TM mode conversion 634–5 tell-and-go (TAG) protocol 1006 tell-and-wait (TAW) protocol 1006–7 Terabus 641 ternary semiconductor alloys 325–6 thermal equilibrium 301, 309 three port couplers 257, 259–64 threshold current density (injection laser) 321, 328 time domain measurement 920–3 total internal reflection 14–16, 30–5 critical angle 15, 18, 20, 22 tramsmissivity (fiber) 95 transducers see sensors transimpedance amplifier, closed loop transfer function 1056 transition rates (between atomic energy levels) 299–302 transmission coefficient (fields) 32–3 transmission distance 825 transmission factor (LED) 402 transmission medium limitations 843–5 transmitted near field 930–2 transmitter 675–9 transoceanic optical fiber networks 1010 transverse electric (TE) modes 28, 31–41 transverse electromagnetic (TEM) waves 28 transverse magnetic (TM) modes 28, 31–41 traveling-wave amplifier (TWA) 552–63, 559–63, 784 traveling-wave photodiode 465–8 traveling-wave semiconductor optical amplifier (TWSOA) 552–553 tree coupler 267–8 triangular profile fiber 46, 135, 136 triple clad (TC) fiber 137 × optical switch 975 in circuit-switched networks 999 unguided modes 40, 53 unitraveling carrier structure 465–6 V-groove flat chip 242 V-groove multiple splice 242 V-groove splices 233, 238–9 1075 V-grooves 263 V number 40, 42, 55, 56 valence band 309–10 vapor axial deposition (VAD) 136, 177, 178–80, 183 vapor phase deposition 175–83 variable optical attenuator 625–6, 644 variance pulse broadening 116 random variable 116, 1053–5 sum of random variable 1055 vertical cavity surface-emitting laser (VCSEL) 347–50 voltage controlled oscillator (VCO) 767, 857 Von Neumann bottleneck 656 W fiber 57, 136, 137 wave interference 26–30 plane 26–8 standing 27 transverse electromagnetic 28 waveband filter (interleaver) 629–33 wave equation 25–6, 31, 36–42 wave packet 29 wave propagation vector 25 wave vacuum propagation constant 25, 26 waveband switching (WBS) 993–5 wavefront 28 waveguide cylindrical 36–42, 46–54 dispersion 113 parameter 127, 132 planar 26–35, 610–15 propagation losses 614 waveguide amplifiers 567, 575–8 wavelength add/drop device (WADD) 974 wavelength continuity constraint 993, 999, 1037 wavelength conversion 583–95, 993 coherent wavelength converters 593–5 cross-absorption modulation converter 592–3 cross-grain modulation converter 584–6 cross-phase modulation converter 586–92 wavelength convertible networks 993 architecture 994 wavelength demultiplexers 269, 270 wavelength division multiplexed networks 976–8, 1020–3, 1033, 1136–8 OPTF_Z02.qxd 9/23/09 10:57 AM Page 1076 1076 Index wavelength division multiplexing (WDM) 257–8, 269–80, 551, 703, 771–7, 785–6, 888, 890–2, 990–1 wavelength routing 977 wavelength routing assignment 996–8 wavelength routing networks 992–8 architecture 994 weakly guiding approximation 36–41 weakly guiding fiber 36–7, 64, 117 Weibull distribution parameter 198 Weibull statistics for failure of fiber under stress 197–8 Wentzel, Kramers, Brillouin (WKB) approximation (graded index fiber) 48–52 wideband fiber amplifiers 581–3 Y junction 616–17 Young’s modulus for fiber 104, 195, 206 yttrium–aluminium–garnet (YAG) 364–5 zero-dispersion slope 131 zero-dispersion wavelength fiber 131 zero material dispersion (ZMD) 127–9, 132, 133 ... LSR LWPF MAC MAN MBE MC MCVD MEMS MESFET MFD MFSK MG-OXC MI MISFET MMF MMI MOSFET MOVPE MPLS MPO MQW MSM MTP MT-RJ MUSE MZI MZM NdDFA NDF Nd : YAG NIU NODG NOLM NRZ NT NZDF NZ-DSF O/E OADM OBPF... near-field method 14.5 Fiber cutoff wavelength measurements 14.6 Fiber numerical aperture measurements 14.7 Fiber diameter measurements 14.7.1 Outer diameter 14.7.2 Core diameter 14.8 Mode-field diameter... 12.14 from Laser automatic level control for optical communications systems in Third European Conference on Optical Communications, Munich, Germany, 14–16 September (S R Salter, S R., Smith, D