Optical fibre, cables and systems

TABLE OF CONTENTS
Page
Foreword ... i
Preface ... iii
CHAPTER 1 – OPTICAL FIBRES CHARACTERISTICS .................................................... 1
Introduction ... 1
1 Single-mode and multimode optical fibres .............................................................................. 1
2 Fibre design issues ... 2
3 Fibre manufacturing methods .................................................................................................. 3
4 Specification of the optical fibres characteristics..................................................................... 4
5 Fibre attributes ... 4
5.1 Core characteristics... 4
5.2 Mode field characteristics ............................................................................................... 6
5.3 Effective area (Aeff ) ... 6
5.4 Cladding characteristics .................................................................................................. 6
5.5 Cut-off wavelength ... 6
5.6 Numerical aperture... 8
5.7 Macrobending loss... 8
5.8 Fibre and protective materials......................................................................................... 8
5.9 Proof-stress level... 9
5.10 Refractive index profile .................................................................................................. 9
5.11 Modal bandwidth ... 9
5.12 Chromatic dispersion ... 10
5.12.1 Chromatic dispersion definitions....................................................................... 11
5.12.2 Chromatic dispersion coefficient....................................................................... 12
5.12.3 Longitudinal uniformity of chromatic dispersion.............................................. 13
6 Cables attributes ... 13
6.1 Attenuation... 13
6.2 Polarization mode dispersion.......................................................................................... 14
7 Link attributes ... 16
7.1 Attenuation... 16
7.1.1 Attenuation of a link.......................................................................................... 16
7.1.2 Wavelength dependence of attenuation ............................................................. 17
7.2 Chromatic dispersion ... 19
7.2.1 Chromatic dispersion of a link........................................................................... 19
7.2.2 Wavelength dependence of chromatic dispersion ............................................. 19
7.3 Differential group delay.................................................................................................. 20
7.4 Non-linear coefficient ... 20
8 Test methods of single-mode optical fibres and cables............................................................ 20
9 Optical fibres types specified by ITU-T................................................................................... 21
9.1 Multimode optical fibres................................................................................................. 21
9.1.1 A 50/125 μm multimode graded index optical fibre cable................................ 21
9.2 Single-mode optical fibres .............................................................................................. 22
9.2.1 The ITU-T first single-mode optical fibre and cable......................................... 22
9.2.2 A dispersion-shifted single-mode optical fibre and cable ................................. 23
9.2.3 A cut-off shifted single-mode optical fibre and cable ....................................... 24
9.2.4 A non-zero dispersion-shifted single-mode optical fibre and cable .................. 24
9.2.5 A fibre and cable with non-zero dispersion for wideband optical transport...... 25
9.2.6 A bending loss insensitive single mode optical fibre and cable for the access
network... 26
CHAPTER 2 – GENERAL CHARACTERISTICS OF OPTICAL CABLES ..................... 27
Introduction ... 27
1 External factors impacting optical cables................................................................................. 27
2 Mechanical and environmental effects on the optical fibres.................................................... 30
2.1 Residual fibre strain ... 30
2.1.1 Causes... 30
2.1.2 Effects... 30
2.1.3 Constructional considerations............................................................................ 30
2.2 Impulsive fibre strain ... 30
2.2.1 Causes... 30
2.2.2 Effects... 32
2.2.3 Constructional considerations............................................................................ 32
2.3 Fibre macrobending ... 32
2.3.1 Causes... 32
2.3.2 Effects... 32
2.3.3 Constructional considerations............................................................................ 32
2.4 Fibre microbending... 32
2.4.1 Causes... 32
2.4.2 Effects... 32
2.4.3 Constructional considerations............................................................................ 32
2.5 Water and moisture... 33
2.5.1 Causes... 33
2.5.2 Effects... 33
2.5.3 Constructional considerations............................................................................ 33
2.6 Hydrogen ... 33
2.6.1 Causes... 33
2.6.2 Effects... 33
2.6.3 Constructional considerations............................................................................ 34
2.7 Lightning... 34
2.7.1 Causes... 34
2.7.2 Effects... 34
2.7.3 Constructional considerations............................................................................ 34
2.8 Nuclear radiation... 34
2.8.1 Causes... 34
2.8.2 Effects... 34
2.8.3 Constructional considerations............................................................................ 34
2.9 Induced voltage... 34
2.9.1 Causes... 34
2.9.2 Effects... 35
2.9.3 Constructional considerations............................................................................ 35
2.10 Biological attack ... 35
3 General structure of optical fibre cables .................................................................................. 35
3.1 Coated optical fibres ... 36
3.1.1 Primary coating of fibres ................................................................................... 36
3.1.2 Secondary protection of fibres........................................................................... 37
3.1.3 Fibre identification ............................................................................................ 41
3.1.4 Optical fibre unit................................................................................................ 41
3.2 Optical cable core structures........................................................................................... 41
3.2.1 Single unit cables............................................................................................... 42
3.2.2 Multiple unit cables ........................................................................................... 44
3.2.3 Protection against moisture ............................................................................... 46
3.3 Strength members ... 47
3.4 Cable sheath and armour................................................................................................. 47
3.4.1 Cable sheath types ............................................................................................. 47
3.4.2 Metal/plastic sheath with metallic tapes or metallic layer................................. 48
3.4.3 Plastic sheath only ............................................................................................. 49
3.4.4 Plastic sheath with strength members................................................................ 49
3.4.5 Plastic sheath with embedded strength members with a metallic tape .............. 49
3.4.6 Cable sheath with armour .................................................................................. 49
3.4.7 Sheath with identification.................................................................................. 50
4 Structure of optical fibre cables for specific installations ........................................................ 50
4.1 Optical fibre cables for aerial applications ..................................................................... 50
4.1.1 Environmental conditions.................................................................................. 50
4.1.2 Cable construction ............................................................................................. 51
4.2 Marinized terrestrial cables............................................................................................. 51
4.2.1 Mechanical and environmental characteristics.................................................. 52
4.2.2 Cable structure................................................................................................... 52
4.3 Submarine cables ... 54
4.3.1 Mechanical and environmental characteristics.................................................. 54
4.3.2 Cable structure................................................................................................... 55
4.4 Optical fibre cables for sewer duct applications ............................................................. 57
4.4.1 Environmental conditions.................................................................................. 57
4.4.2 Cable structure................................................................................................... 57
4.5 Optical fibre cables for multidwelling FTTH indoor applications: riser cable ............... 58
4.5.1 Environmental conditions.................................................................................. 58
4.5.2 Cable structure................................................................................................... 59
5 Cable tests ... 60
CHAPTER 3 – OPTICAL CABLE INSTALLATION.............................................................. 61
Introduction ... 61
1 Cable installation methods ... 61
1.1 Installation of cables in underground ducts .................................................................... 61
1.1.1 Route considerations.......................................................................................... 61
1.1.2 Cable installation tension prediction for cables pulled into ducts ..................... 62
1.1.3 Cable overload protection methods ................................................................... 63
1.1.4 Winching equipment and ropes ......................................................................... 64
1.1.5 Guiding systems and cable bending .................................................................. 64
1.1.6 Cable friction and lubrication............................................................................ 64
1.1.7 Cable handling methods to maximize installed lengths by pulling ................... 64
1.1.8 Air-assisted cable installation............................................................................ 65
1.1.9 Water pumping system ...................................................................................... 65
1.1.10 Jointing length allowance .................................................................................. 66
1.2 Installation of optical cables with the trenchless technique ............................................ 66
1.2.1 Trenchless techniques and their applications .................................................... 67
1.3 Installation of optical cables with the mini-trench technique ......................................... 69
1.3.1 Traditional mini-trench (10 × 30 cm) ................................................................ 69
1.3.2 The enhanced mini-trench ................................................................................. 71
1.4 Installation of optical cables with the micro-trench technique ....................................... 72
1.4.1 Micro-trench preparation and duct/cable laying................................................ 73
1.5 Installation of aerial cables ............................................................................................. 74
1.5.1 Installation methods........................................................................................... 74
1.5.2 Cable protection methods .................................................................................. 74
1.5.3 Winching and guiding systems.......................................................................... 75
1.5.4 Methods to maximize lengths............................................................................ 75
1.5.5 Jointing length allowance .................................................................................. 75
1.5.6 In-service considerations ................................................................................... 75
1.6 Installation of buried cables ............................................................................................ 76
1.6.1 Installation methods........................................................................................... 76
1.6.2 Cable guiding and protection............................................................................. 76
1.6.3 Methods to maximize lengths............................................................................ 76
1.6.4 Jointing length allowance .................................................................................. 77
1.7 Installation of cables in tunnels and on bridges .............................................................. 77
1.8 Installation of optical fibre ground wire (OPGW) cable................................................. 77
1.9 Installation of optical cables along railways ................................................................... 78
1.9.1 Duct installation................................................................................................. 79
1.9.2 Directly buried cable installation....................................................................... 79
1.9.3 Aerial installation .............................................................................................. 79
1.9.4 Cable installation along existing railway poles ................................................. 79
1.9.5 Particular cases .................................................................................................. 80
1.9.6 Splice points along railways .............................................................................. 80
1.10 Installation of cables in sewer ducts ............................................................................... 80
1.10.1 Sewer assessment .............................................................................................. 81
1.10.2 Installation in non-man-accessible sewers......................................................... 81
1.10.3 Installation in man-accessible sewers................................................................ 82
1.10.4 Installation of special armoured optical cables into the sewer ducts................. 82
1.10.5 Guidelines for the selection of the most appropriate installation method ......... 83
1.10.6 Pressure washing and finishing brush ............................................................... 83
1.10.7 Safety... 83
1.11 Installation of marinized and submarine optical cables .................................................. 84
1.11.1 Survey and route planning................................................................................. 84
1.11.2 Characteristics of vessels................................................................................... 85
1.11.3 Installation ... 87
1.11.4 Controls after the laying .................................................................................... 89
1.12 Installation of indoor cables............................................................................................ 90
2 Safety, in-service protection and location ................................................................................ 90
2.1 Safety ... 90
2.2 In-service protection ... 90
2.3 Location ... 90
CHAPTER 4 – OPTICAL SPLICES, CONNECTORS AND PASSIVE NODES ............... 91
Introduction ... 91
1 Optical fibre splices... 91
1.1 Splice losses... 91
1.2 Fusion splices... 92
1.3 Mechanical splices ... 92

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