Optical Networks: A Practical Perspective - Part 85 docx

810 INDEX large effective area fiber (LEAF), 94-95 choosing, 342 dispersion profile, 94 distribution of power, 95, 96 refractive index profile, 95 See also optical fiber(s) large electronic switches, 215-216 large optical switches, 201-207, 224 blocking characteristics, 202-203 build considerations, 201-203 loss uniformity, 202 number of crossovers, 202 number of switch elements, 202 See also optical switches LARNET WRPON, 607-608 laser arrays, 185-186 lasers, 166-176 coherent output, 168 distributed-feedback (DFB), 37, 169-171 edge-emitting, 173 external cavity, 171-172 Fabry-Perot (FP), 168, 186 fiber, 166 grating coupler sampled reflector (GCSR), 183, 185, 186 local-oscillator, 263 longitudinal modes, 168-169 mode-locked, 174-176 multiple-longitudinal mode (MLM), 168, 169 principle of operation, 167-168 sampled grating (SG) DBR, 183, 184-185 semiconductor, 166, 526 single-longitudinal mode (SLM), 37, 168, 169 super-structure grating (SSG) DBR, 183, 184-185 tunable, 178-186 vertical cavity surface-emitting, 173-174 VGF, 183-184 lasing loops, 298-299 effects, 298 handling methods, 298 lasing threshold, 168 latching switches, 201 layered network architecture, 16-20 classical, 18-19 data flow between layers, 17 data link layer, 18-19 hierarchy illustration, 17 IP over ATM over SONET network, 20 IP over SONET network, 19-20 multiplexing example, 23 network layer, 19 physical layer, 18 SONET layer, 22, 23 transport layer, 19 See also optical layer L-band, 316 C-band vs., 689 EDFAs, 158-159, 289 positive chromatic dispersion fibers and, 97 See also C-band Lead service class, 567 light-emitting diodes (LEDs), 176-178 light output, 177 slicing, 177-178 lightpaths, 15,403,504 average lease time, 466 bandwidths, 502 circuit-switched, 428 dedicated, 447 full-duplex, 485 optical layer, 21 permanent, 21 protecting, 420, 428-429 protection routes per, 580 sets of, 475 setting up/taking down, 403 "single-hop," 443 undirected, 455 lightpath topologies, 405-406, 440, 442-443 all-optical, 442, 445-446 congestion vs. node degree, 454 designing, 449, 453 hub design, 442, 444-445 PWDM ring, 442, 443 SONET rings, 454 of three-node network, 440 lightpath topology design (LTD) problem, 440, 449-454 bidirectional lightpath constraint, 451 congestion parameter, 450 degree constraints, 451 flow conservation at nodes, 450 flow control on logical link, 451 formulation, 449-450 LTD-LP, 452, 453 LTD-MILP, 452, 453 INDEX 811 nonnegativity and integer constraints, 451 objective function, 450 light propagation, 50-64 in dielectric waveguides, 63-64 geometrical optics approach, 50-55 wave theory approach, 55-64 limited wavelength conversion, 457-458 illustrated, 458 switch cost savings, 458 WA problem, 459 See also wavelength conversion line amplifiers, 290 linear dielectric polarization, 82 linearity, 5 7-58 linear polarization, 61,742 linear program (LP), 452 LTD, 452, 453 relaxation, 452 linear susceptibility, 741 line coding, 241 line layer, 370 line network, 476 illustrated, 476 with N nodes, 481 line overhead bytes, 374-375 illustrated, 373 See also SONET frame structure line terminating equipment (LTE), 378 liquid crystal switches, 212-213,214 illustrated, 214 principle of operation, 213 lithium niobate external modulator, 188 with directional coupler configuration, 189 with MZI configuration, 190 livelock, 649 load imped~.~nce, 745 local-area networks (LANs), 4, 381 local-exchange carriers (LECs), 3 competitive (CLECs), 4 incumbent (ILECs), 3 locality of response, 56 local muhipoint distribution service (LMDS), 597 local-oscillator lasers, 263 logical AND operations, 625-630 nonlinear optical loop mirror (NOLM) for, 626-629 output, 623 soliton-trapping AND gate for, 629-630 long-haul interoffice connections, 377 long-haul networks, 4, 688-698 capabilities and costs, 691,694 case study, 689-696 C-band, 689 cost breakdown, 695 equipment and crossconnects, 691,695 handoff, 5 infrastructure, 5 link distances, 692 traffic mix, 690 transponders/amplifiers relative cost, 693,696 undersea, 697-698 WDM, 376, 689 See also ultra-long-haul (ULH) networks longitudinal component, 61 long-period fiber gratings, 127-132 fabrication, 127 principle of operation, 128-132 transmission spectrum, 129 See also fiber gratings; gratings loop mirror, 226 lOSS attenuation, as function of wavelength, 66 AWG, 140 bandwidth and, 65-68 bending, 67-68 differential, 641 due to Rayleigh scattering, 67 excessive, 110 insertion, 113,200-201,209 mechanisms, 65 in optical fiber, 31-32 optical power and, 31-32 parallel OADM architecture, 412 polarization-dependent (PDL), 110, 201 serial OADM architecture, 414-415 uniformity, 202 losslessness, 58 loss-of-signal (LOS) alarms, 507 low-loss transmission, 49 Mach-Zehnder interferometers, 109, 135-139, 188,220 crosstalk performance, 137 illustrated, 136 lithium niobate external modulator using, 190 multistage, 138-139 narrow band, 137 812 INDEX Mach-Zehnder interferometers (continued) principle of operation, 137-139 transfer functions, 138,228 uses, 136, 137 magnetic flux density, 56 magnetic polarization, 56 management protocols, 500-501 CMIP, 501 SNMP, 501 management standards, 722-723 Manhattan Street network, 646, 647-648 diameter, 648 illustrated, 646 Markov chain, 466 master, 528 material absorption, 65-66 material dispersion, 68, 69 maximum load dimensioning models, 475-482 offline lightpath requests, 475-481 online RWA in rings, 475,481-482 shortcomings, 475 max-used algorithm, 474 Maxwell distribution, 753 Maxwell's equations, 55, 727-729 mechanical tuning, 179 media access control layer (MAC), 19 medium homogeneous, 58 isotropic, 57 linear, 57-58 locality of response, 56 lossless, 58 mesh protection schemes, 576-581 centralized implementation, 580-581 complexity, 579 deployment issues, 579-580 distributed implementation, 581 past usage of, 478 resurrection of, 478 variations, 580-581 metro networks, 4-5, 698-703 access, 4-5, 698, 699 case study, 700-703 interoffice, 5,698-699 optical amplifiers in, 700 traffic distribution changes, 699 WDM deployment in, 699 See also networks metropolitan-area networks (MANs), 4, 39, 381 micro-electro-mechanical system (MEMS) switches, 209-212 3D, 212 analog beam-steering mirror, 210 fabrication techniques, 211-212 n • n switch using mirrors, 211 two-state pop-up mirror, 209, 210 See also optical switches mid-span spectral inversion (MSSI), 319 midstage access, 408 mixed integer linear program (MILP), 452 LTD, 452, 453 value approximation, 453 mixing probability, 473 mode-locked lasers, 174-176 amplitude modulation illustration, 177 gain, 176 output oscillation, 175 time interval between pulses, 176 See also lasers modular OADM architecture, 412, 413 modulation, 186, 239-242, 272 cross-gain (CGM), 219-220 cross-phase (CPM), 83, 89-90, 220-223 design considerations, 343 direct, 38, 186-187 external, 38, 187-190 instability, 97 multilevel, 249 on-off keying (OOK), 186-190, 239-240 optical duobinary, 246-248 optical single sideband (SSB), 248-249 self-phase (SPM), 76, 83-88 subcarrier, 242-245 vestigial sideband (VSB), 249 See also demodulation monochromatic plane waves, 83 multicasting, 502 multichannel multipoint distribution service (MMDS), 597 multifiber rings, 480-481 multilayer thin-film filters, 743-750 cavities, 747 design, 747-750 single cavity, 749 three-cavity, 750 transfer functions, 746, 748, 749 two-cavity, 749 wave propagation and, 743-747 INDEX 813 multilevel modulation, 249 multilongitudinal mode (MLM) Fabry-Perot lasers, 34-35, 36 multimode fiber, 33-35, 60 core diameters, 33 geometrical optics model, 33, 35 graded-index, 53 propagation modes, 60 step-index, 53 See also optical fiber multiple-longitudinal mode (MLM) laser, 168, 169 multiplexers, 115 add/drop (ADMs), 378 high channel count architectures, 148-151 misalignment, 345 SONET, 365 stacked-up, 365 multiplexing, 618 asynchronous, 365 cost reduction, 365 frequency division (FDM), 13 illustrated, 13 optical time division (OTDM), 12-13 SONET/SDH, 364-366, 367-371 subcarrier (SCM), 243-245 techniques, 12-14 time division (TDM), 12-13, 41,603, 619-631 two-stage approach, 150 See also wavelength division multiplexing (WDM) multiplex section layer, 370 multiprotocol label switching (MPLS), 9, 392-394, 558 ATM and, 394-395 bandwidth reservation, 393 benefits, 393 design philosophy, 393 forwarding hardware optimization, 393 label-switched path (LSP), 392 paradigm, 393 VPN support, 394 multiservice platforms (MSPs), 679-681 development of, 679 ring configuration deployment, 681 service delivery, 680 multistage banding, 148-149 multistage interleaving, 149-151 multistage MZI, 138-139 multivendor interoperability, 505-507 narrowband DCS, 380 negative dispersion fibers, 95-98 network elements, 497 agents, 497-498 element management system (EMS), 497-499 types of, 497 network file system (NFS), 390 network interface units (NIUs), 593, 598 dedicated bandwidth, 594 illustrated, 594 optics/electronics, 594 shared bandwidth, 594, 595 in switched networks, 593 network layer, 19 network management accounting management, 497 adaptation management, 496, 524-526 configuration management, 496, 519-526 connection management, 496, 520-524 cost, 495, 530 equipment management, 519-520 fault management, 496, 503,507-519 framework, 497-499 function decentralization, 497 functions, 495-497 hierarchical performance of, 497 implementation, 497 information model (IM), 499-500 overview illustration, 498 performance management, 495-496, 507-519 protocols, 500-501 security management, 496-497 summary, 530-531 network management system (NMS), 499 networks access, 4-5, 591-612 agile, 704 all-optical, 24-26 ATM, 9, 381 cable, 595 circuit-switched, 6-7 crosstalk in, 303 diameter, 647 distributed control, 496 distribution, 593 814 INDEX networks (continued) ESCON, 12, 21 evolution, 667-681 hybrid fiber coax (HFC), 596 integrated services digital (ISDN), 597 interoffice, 5 IP over SONET, 19-20 line, 476 long-haul, 4, 5, 688-698 Manhattan Street, 646, 647-648 metro, 4-5, 698-703 next-generation, 673-681 nontransparent, 25 opaque, 704 packet-switched, 7-9 photonic packet-switched (PPS), 615-660 practical, 25 public, illustrated, 5 ring, 431,432, 473,478-479 scalable, 669 survivability, 537-587 telephone, 595 transparency, 24-26 twisted-pair, 596 ultra-long-haul, 690-691,694-695 undersea, 5, 697-698 wavelength-routing, 15,403,462-464 See also optical networks; SDH networks; SONET; WDM systems network-to-network interface (NNI), 382, 385, 523 next-generation networks, 673-681 architectural choices, 673-681 illustrated, 680 nodes failures, 538,553-554 Manhattan Street network, 646 PPS, 619 remote (RNs), 593, 594 routing, 616, 617 shufflenet, 646, 647 noise amplifier, 760-762 APD, 255 ASE, 337 beat, 256 front-end amplifier, 254-255 shot, 253, 254, 759 signal-dependent, 288 thermal, 253,254 noise figure, 255 amplifier, 257 front-end amplifier, 255 input coupling loss and, 258 nonblocking switches, 202-203 noncompliant wavelength interface, 525 nonlinear amplifying loop mirror (NALM), 627 nonlinear dielectric polarization, 83 CPM, 89 four-wave mixing (FWM), 91, 92 SPM, 84, 85 nonlinear effects, 76-98, 323-335 categories, 76, 323 cross-phase modulation (CPM), 333-335 effective area, 77-79 effective length, 77-79, 323-325 four-wave mixing (FWM), 76, 329-333 limitations, 323-335 minimizing, 344 on pulse propagation, 735-738 peak transmit power limit, 288 propagation and, 81-83 role of chromatic dispersion management, 335 self-phase modulation (SPM), 76, 333-335 stimulated Brillouin scattering (SBS), 76, 77, 79-80, 325-326 stimulated Raman scattering (SRS), 76, 77, 80-81,326-329 transmit power and, 344 nonlinear index coefficient, 85 nonlinear length, 737 nonlinear optical loop mirror (NOLM), 623, 626-629 elements, 626 experiments, 627 illustrated, 627 nonlinear amplifying loop mirror (NALM) and, 627 terahertz optical asymmetric demultiplexer (TOAD), 627-628 nonlinear polarization, 741-742 nonlinear propagation coefficient, 736 nonlinear Schr6dinger equation (NLSE), 737 non-return-to-zero (NRZ) modulation, 240-242 advantages, 241 bit rate and, 312 chromatic dispersion limits, 309-311 INDEX 815 PMD and, 322 uses, 242 See also signal formats nonrevertive protection, 540 nontransparent networks, 25 nonzero-dispersion fiber (NZ-DSF), 93-94 choosing, 342 chromatic dispersion, 93,316 dispersion slopes, 94 for submarine systems, 342 TeraLight, 93 for terrestrial systems, 342 See also optical fiber(s) normalized propagation constant, 61 NP-complete problems, 461 OCh-Mesh protection, 576-581 OCh-SPRing protection, 575-576 offered load, 467 offline lightpath requests, 475-481 offline RWA problem, 462 OMS-DPRing protection, 571,572 illustrated, 572 implementations, 571 See also optical layer protection OMS-SPRing protection, 571-573 after failure, 574 illustrated, 573 ring switching, 574 span switching, 574 two-fiber version, 573 See also optical layer protection online RWA problem, 462-463,475, 481-482 on-off keying (OOK) modulation, 186-190, 239-240 DC balance, 241 direct, 186-187 external, 187-190 illustrated, 240 non-return-to-zero (NRZ) format, 240-242 return-to-zero (RZ) format, 240-242 signal formats, 240-242 See also modulation opaque networks, 704 open fiber control (OFC) protocol, 528-530, 534 functioning of, 528-529 illustrated, 428 state machine run by each node for, 529 Open Shortest Path First (OSPF), 391 operations support system (OSS), 499 optical add/drop multiplexers (OADMs), 15, 40, 41,403, 408-419, 429-430, 679 architecture comparison, 414 architecture illustrations, 413 architectures, 411-4 16 band drop architecture, 413,416 benefits, 409 410 illustrated, 404 implementation, 15-16 inflexibility, 410 key attributes, 411-412 line ports, 15 in metro ring case study, 701 modular architecture, 412, 413 parallel architecture, 412, 413 reconfigurable, 417-419 role illustration, 409 serial architecture, 413, 414-416 single-channel OADM (SC-OADM), 414 use of, 403,408-409 in wavelength-routing network, 16 WDM ring using, 561 optical amplifiers, 151-165,289-299, 408 advantages, 151 block diagram, 408 cascades, 293-294 configurations, 290 drawbacks, 151 erbium-doped fiber amplifiers (EDFAs), 154-159 Fabry-Perot amplifier, 167 gain saturation, 291 in metro networks, 700 midstage access, 408 noise, 760-762 at periodic intervals, 100 Raman amplifiers, 159-161 semiconductor (SOAs), 161-165 spacing penalty, 294-296 spontaneous emission, 152, 153 stimulated emission, 152-153 types of, 151 See also line amplifiers; optical preamplifiers; power amplifiers optical buffers, 28 optical channel (OCh) layer, 504-505 path (OCh-P), 505 section (OCh-S), 505 transparent section (OCh-TS), 505 816 INDEX optical channel-path trace, 509 optical channel-section trace, 509 optical channel-transparent section trace, 509 optical crossconnects (OXCs), 15, 40, 41,380, 403, 430, 463 all-optical, 422, 424, 425-428 bit rate transparency, 420 configuration comparison, 423 configurations, 421-422 as cost-effective passthrough, 419 electrical core, 428 functions, 403-404 illustrated, 404 multiplexing and grooming, 421 network use illustration, 420 OLT system integration, 424-425 optical core, 428 performance monitoring, 420-421 port complex, 421 ports, 419, 422 protection, 420 reconfigurability and, 419 service provisioning, 420 size of, 463-464 switch core, 421,422, 423 test access, 421 wavelength conversion, 421 wavelength plane, 427-428 in wavelength-routing network, 16 optical duobinary modulation, 246-248 bandwidth advantage, 247 error propagation and, 247 ternary signaling scheme, 247 optical fiber(s), 10, 12 attenuation coefficient measurement, 349 bundles, 683 capacity limits, 249-250 choice, 341-342 cladding, 33 core material, 33 cross section, 50 in design consideration, 341-342 dispersion-shifted (DSF), 36, 75 graded-index, 53 LEAF, 94-95 light propagation in, 50-64 longitudinal section, 50 loss, 31-32 low-loss, 33 multimode, 33-35, 60 new types of, 93-98 nonzero-dispersion (NZ-DSF), 93-94 propagation of signals in, 49-104 pulse propagation in, 731-740 single-mode, 35-37, 54, 59 standards, 721 step-index, 53 transmission system evolution, 34 optical gating, 218-220 optical layer, 20-24 client layers of, 363-400 fault handling, 563 functions, 504 layers within, 504-505 lightpaths, 21 network-to-network interface (NNI), 523 optical channel (OCh) layer, 504-505 optical multiplex section (OMS) layer, 504-505 optical transmission section (OTS) layer, 504-505 services and interfacing, 502-504 user network interface (UNI), 523 See also layered network architecture optical layer overhead, 514-519 applications of, 515 digital wrapper overhead, 518-519 illustrated, 514 optical supervisory channel (OSC), 516-518 pilot tone, 516-517 rate-preserving overhead, 518 techniques, 514, 515-519 optical layer protection, 560-582, 584 1+10Ch, 569, 570, 574-575 1§ 569, 570 1:10MS, 571 I:N transponder, 573 bandwidth, 563 benefit, 562, 564 configuration illustration, 561,562 cost savings, 560 efficiency, 563 for enhancing SONET protection, 565 example, 564 OCh-Mesh, 576-581 OCh-SPRing, 575-576 INDEX 817 OMS-DPRing, 571,572 OMS-SPRing, 571-573 operating in optical channel layer, 568 operating in optical multiplex section (OMS) layer, 568 for resilience, 563-564 routes, 566 schemes, 567-582 summary, 568 technique selection, 582 wavelength, 563 See also protection optical line terminals (OLTs), 15, 41,403, 406-408, 429, 677 block diagram, 406 deployment, 15 functional elements, 406 illustrated, 404 optical amplifiers, 406 optical supervisory channel (OSC), 407-408 overhead, 407 OXC system integration, 424-425 transponders, 406-407 use of, 403 wavelength multiplexers, 406 in wavelength-routing network, 16 optical multiplex section (OMS), 504 optical networks bandwidth, 10 deployment drivers, 1-2 evolution, 32-40 first generation, 12 introduction to, 1-42 passive (PONs), 600 problems solved by, 10 second generation, 14-16 See also networks optical network units (ONUs), 599-607 different wavelength direction to, 606 performing NIU function, 599 specific time slot assignment to, 603 TDM approach and, 603 for upstream channel, 603 optical packet demultiplexers, 659 optical packet switching, 26-28 mission of, 27-28 nodes, 27, 28 optical path trace, 509 optical phase lock loop, 633-634 optical power, 31-32 optical preamplifiers, 255-258,290 design, 290 receivers with, 256 See also optical amplifiers optical safety, 526-530 optical single sideband (SSB) modulation, 248-249 implementation, 248 uses, 249 optical SNR (OSNR), 262-263 degradation, 293 measured, 263 obtaining, 263 optical supervisory channel (OSC), 407-408, 498, 516-518 illustrated, 516 location, 517 uses, 516, 518 wavelength choice, 516, 517 See also optical layer overhead optical switches, 199-216 applications, 199, 200 Bene~, 206-207 bubble-based waveguide, 212, 213 bulk mechanical, 207-209 Clos, 204-205 crossbar, 203-204 crosstalk, 201 electro-optic, 213-214 extinction ratio, 200 insertion loss, 200-201 large, 201-207 latching, 201 liquid crystal, 212-213,214 micro-electro-mechanical system (MEMS), 209-212 in packet-switched networks, 200 parameters, 200-201 reliability, 201 SOA, 214-215 Spanke, 205-206 Spanke-Bene~, 207 technologies, 207-215 technology comparison, 208 thermo-optic, 214 optical time division multiplexing (OTDM), 12-13,619-631 aggregate rate, 619 bit interleaving, 620-623 818 INDEX optical time division multiplexing (continued) electronic TDM vs., 619 fixed, 27 framing pulses, 620 illustrated, 621 implementation, 12 packet interleaving, 623-625 statistical, 27 optical-to-electrical-to-optical (OEO) converters, 27, 407 optical trace, 509 optical transmission section (OTS), 504-505 optimum decision rule, 258 optoelectronic regeneration, 217-218 output buffering, 637-639 with fiber delay lines, 642 with multiple wavelengths, 642 switches, 638 switching multiple input wavelengths, 644 See also buffering overlay model, 523 overlay plus model, 523, 524 packet buffers, 638 packet interleaving, 623-625 demultiplexing operation, 625, 626 function illustration, 621 optical multiplexer, 624 packet layer, 616 packet-over-SONET (POS), 389 packets, 7 assured forwarding (AF), 392 buffered, 8 delay, 645-647 Diff-Serv packets, 392 expedited forwarding (EF), 392 flood, 390 link state, 390, 391 loss probability, 637 lost, 391,558 LSP, 393, 559 misrouted, 637, 645 queued, 8 sent by end node, 616 packet-switched networks, 7-9 best-effort service, 8 frame relay, 8 invention of, 7 optical, 26-28 packet header, 7 packets, 7 statistical multiplexing, 7-8 switches in, 200 parallel OADM architecture, 412, 413 fully tunable OADM with, 417, 418 illustrated, 413 loss, 412 partially tunable OADM with, 417, 418 parameters, this book, 717-719 passive optical networks (PONs), 600 architecture comparison, 601 evolution, 608-610 power budget calculation, 611 TPON, 603-604 wavelength-routed, 609-610 WDM components, 607 WPON, 595, 605 WRPON, 605-608 See also optical networks passive photonics loop (PPL), 606 path graph, 461 path layer, 370 path overhead bytes, 375 illustrated, 373 See also SONET frame structure peer model, 523, 524 performance management, 495-496, 507-519, 530 BER measurement, 509 impact of transparency, 508 See also network management performance monitoring, 420-421 permittivity of vacuum, 56 phase, 732 conjugation, 319 masks, 126 mismatch, 330 shifts, 118 phase lock loop (PLL), 266 phase-shift keying (PSK), 278 phase velocity of pulse, 732 of wave, 732 photocurrent autocorrelation of, 758 autovariance, 759 spectral density, 759, 761 INDEX 819 photodetectors, 192-197, 250 avalanche (APD), 255, 275 efficiency, 193 materials, 192, 193-194 operating bandwidth, 194 photodiode, 195-197 principle, 192, 193 responsivity, 194 photodiodes, 195-197 avalanche, 197 bandwidth, 198 noise performance, 198 pin, 195-197 photonic packet-switched (PPS) networks, 615-660 block diagram, 617 buffering, 618, 635-649 burst switching, 649-650 feedback configuration, 636-637 feed-forward architecture, 636 functions, 618-619 header processing, 634-635 link speed, 617 nodes, 619 OTDM, 619-631 research, 619 summary, 657 synchronization, 618-619, 631-634 See also PPS testbeds physical layer, 18 designing, 283-284 interfaces, 382 link initialization and take-down, 284 power penalty and, 284-287 SONET, 370 physical topology, 440 piezoelectric filters, 133 pilot tones, 516-517 advantages/disadvantages, 516 frequency, 515, 516 pinFET, 199 pin photodiodes, 195-197 illustrated, 197 receiver sensitivity, 261 structure, 196 See also photodiodes plain old telephone service (POTS), 591 Planck's constant, 252 Platinum service class, 567 plesiochronous digital hierarchy (PDH), 364 problems, 364 SONET/SDH vs., 364-366 transmission rates, 365 pn-junctions, 163, 166, 195 forward-biased, 164 reverse-biased, 195, 196 PNNI (private network-to-network interface) routing, 387-388 goal, 388 signaling protocol, 388 points of presence (POPs), 4 point-to-point links, 351,403 OLTs in, 403 protection, 544-546 point-to-point protocol (PPP), 18, 388 point-to-point WDM (PWDM) ring, 442 architecture, 443 example, 443-444 illustrated, 442 number of wavelengths, 447 router ports, 447 See also lightpath topologies Poisson distribution, 753-754 Poisson random processes, 755-756 polarization, 61-63, 82 dielectric, 56, 82 induced electric, 56 interfering signals, 286 linear, 61,742 magnetic, 56 nonlinear, 741-742 orthogonal, 62 state of (SOP), 62, 113 transverse, 61 polarization-dependent loss (PDL), 63, 110, 322-323 bulk mechanical switches, 209 total, 323 polarization-mode dispersion (PMD), 62, 320-323 compensation, 321-322 distance limit due to, 684 effects, 62, 63 first-order, 322 illustrated, 63 as impediment, 308 imposed limitations, 320, 321 intersymbol interference (ISI), 321 NRZ modulation and, 322 . channel (OCh) layer, 50 4-5 05 path (OCh-P), 505 section (OCh-S), 505 transparent section (OCh-TS), 505 816 INDEX optical channel-path trace, 509 optical channel-section trace, 509 optical. optical amplifiers, 15 1-1 65,28 9-2 99, 408 advantages, 151 block diagram, 408 cascades, 29 3-2 94 configurations, 290 drawbacks, 151 erbium-doped fiber amplifiers (EDFAs), 15 4-1 59 Fabry-Perot. 509 optical phase lock loop, 63 3-6 34 optical power, 3 1-3 2 optical preamplifiers, 25 5-2 58,290 design, 290 receivers with, 256 See also optical amplifiers optical safety, 52 6-5 30 optical