On Optical Communication: Reflections and Perspectives Herwig Kogelnik BellLabs,LucentTechnologies,CrawfordHillLab,Holmdel,NJ07733,USA:herwig@lucent.com Abstract Optical communication has advanced into the tera-era deploying 1/2 terameter of fiber and carrying several Tb/s per fiber. Remaining challenges include extending the success of point-to-point long-haul to metropolitan networks and broadband access applications Introduction AT&T long-haul network in 1995/1996 marks another Reflecting on the past 15 years of optical milestone in optical communications and the ommunication, one can only marvel at the amazing beginning of the WDM revolution. This large-scale advances in this technology and in its applications. installation of WDM systems involved thousands of Technical progress seems to continue in spite of the optical fiber amplifiers and hundreds of WDM SONET recent burst of the telecom bubble. At the end of terminals. 1.3 1994, a little less than ten years ago, somewhat more than 50 million km of optical fiber had been deployed worldwide for all applications. Today more than 500 Terabits Capacity per Fiber million km, i.e. one half of a terameter, are deployed. In addition to the new WDM components, researchers More than 10 percent of this deployment is conceived of new WDM system techniques attributable to recent installations in China. It is good counteracting fiber impairments such as dispersion to remind ourselves that a fiber of 0.5 Tm length ca and nonlinearities and allowing transmission at higher be wound more than 10 000 times around the earth capacities over longer distances. This includes the discipline of dispersion management, where In 1988 our technical community celebrated a major detrimental nonlinear effects are balanced by a clever milestone in optical fiber communication This was the choice of local fiber dispersion. In 1996 three deployment of the transatlantic fiber system TAT8 laboratories" simultaneously demonstrated system linking Europe and North America using about 6000 research experiments achieving transmission at the km of optical fiber cable. By 1991 fiber carried more milestone capacity of 1 Terabit/second per fiber. In information traffic over international digital links than 2001, right on schedule with the traditional trend of communication satellites. Today a map of the global increasing capacity by a factor of ten every five years, undersea fiber network looks like a spider web two laboratories accomplished transmission covering the globe with more than 600 000 km of fiber capacities of 10 Tb/s. The next milestone would be cable. And there is news of new construction of 100 Tb/s in 2006. However, there are not many who undersea systems, particularly in the Indian Ocean expect that this can be accomplished, in particular as region, including the Falcon, SEA-ME-WE 4, and attention is shifting to lower cost systems and ultra Polarnet systems long-haul (ULH)transmission Today, modern commercial transmission systems WDM and optical Amplifiers offer capacities of several Tb/s per fiber as illustrated The early 1990,s witnessed a vigorous worldwide in one vendor's table" shown below. The table also effort to ready the network elements and components shows the trend of system transmission capabilities for wavelength division multiplexing (WDM). These expressing progress better than words. Note the ULH included WDM laser sources, erbium-doped fiber of 4000 km spans, the 5 petabit/s km amplifiers, WDM routers and others WDM provided capacity distance product, and the 40 Gb/s bit-rate the parallelism needed to maintain increases in the per WDM channel. other recent advances include the transmission capacity per fiber at the rate of 100 use of Raman fiber amplifiers, of advanced forward every 10 years. It also provided a new degree of error correction(FEC), and of WDM laser sources freedom and flexibility for the design of networks by tunable over 100 WDM channels. Further systems adding the wavelength dimension to the traditional advances are expected from new modulation formats etwork dimensions of space and time the economic such as Rz-DPSK offering more tolerance to system benefits of WDM were enabled by the optically impairments and/or better bandwidth efficiency transparent amplifiers that can be shared between many WDM channels. Optical Networking The extensive deployment of WDM technology in the As the cost of optics is driven down, the applications of fiber communication are expanding from long-haul
On Optical Communication: Reflections and Perspectives Herwig Kogelnik Bell Labs, Lucent Technologies, Crawford Hill Lab, Holmdel, NJ 07733, USA: herwig@lucent.com Abstract Optical communication has advanced into the tera-era deploying 1/2 terameter of fiber and carrying several Tb/s per fiber. Remaining challenges include extending the success of point-to-point long-haul to metropolitan networks and broadband access applications. Introduction Reflecting on the past 15 years of optical communication, one can only marvel at the amazing advances in this technology and in its applications. Technical progress seems to continue in spite of the recent burst of the telecom bubble. At the end of 1994, a little less than ten years ago, somewhat more than 50 million km of optical fiber had been deployed worldwide for all applications. 1 Today more than 500 million km, i.e. one half of a terameter, are deployed. More than 10 percent of this deployment is attributable to recent installations in China. It is good to remind ourselves that a fiber of 0.5 Tm length can be wound more than 10 000 times around the earth. In 1988 our technical community celebrated a major milestone in optical fiber communication. This was the deployment of the transatlantic fiber system TAT8 linking Europe and North America using about 6000 km of optical fiber cable. By 1991 fiber carried more information traffic over international digital links than communication satellites. Today a map of the global undersea fiber network looks like a spider web covering the globe with more than 600 000 km of fiber cable.2 And there is news of new construction of undersea systems, particularly in the Indian Ocean region, including the Falcon, SEA-ME-WE 4, and Polarnet systems. WDM and Optical Amplifiers The early 1990’s witnessed a vigorous worldwide effort to ready the network elements and components for wavelength division multiplexing (WDM). These included WDM laser sources, erbium-doped fiber amplifiers, WDM routers and others. WDM provided the parallelism needed to maintain increases in the transmission capacity per fiber at the rate of 100 every 10 years. It also provided a new degree of freedom and flexibility for the design of networks by adding the wavelength dimension to the traditional network dimensions of space and time. The economic benefits of WDM were enabled by the optically transparent amplifiers that can be shared between many WDM channels. The extensive deployment of WDM technology in the AT&T long-haul network in 1995/1996 marks another milestone in optical communications and the beginning of the WDM revolution. This large-scale installation of WDM systems involved thousands of optical fiber amplifiers and hundreds of WDM SONET terminals.1,3 Terabits Capacity per Fiber In addition to the new WDM components, researchers conceived of new WDM system techniques counteracting fiber impairments such as dispersion and nonlinearities and allowing transmission at higher capacities over longer distances. This includes the discipline of dispersion management, where detrimental nonlinear effects are balanced by a clever choice of local fiber dispersion. In 1996 three laboratories4,5,6 simultaneously demonstrated system research experiments achieving transmission at the milestone capacity of 1 Terabit/second per fiber. In 2001, right on schedule with the traditional trend of increasing capacity by a factor of ten every five years, two laboratories7,8 accomplished transmission capacities of 10 Tb/s. The next milestone would be 100 Tb/s in 2006. However, there are not many who expect that this can be accomplished, in particular as attention is shifting to lower cost systems and ultralong-haul (ULH) transmission. Today, modern commercial transmission systems offer capacities of several Tb/s per fiber as illustrated in one vendor’s table9,10 shown below. The table also shows the trend of system transmission capabilities expressing progress better than words. Note the ULH capability of 4000 km spans, the 5 petabit/s.km capacity distance product, and the 40 Gb/s bit-rate per WDM channel. Other recent advances include the use of Raman fiber amplifiers, of advanced forward error correction (FEC), and of WDM laser sources tunable over 100 WDM channels. Further systems advances are expected from new modulation formats such as RZ-DPSK11 offering more tolerance to system impairments and/or better bandwidth efficiency. Optical Networking As the cost of optics is driven down, the applications of fiber communication are expanding from long-haul
point-to-point systems to multipoint metropolitan end user. In this connection we will observe with great networks and to broadband access the new ulh interest the evolution of new network architectures capabilities promise to enable all-optical networks. the growth of 10-Gb Ethernet, and the fiber-to-the Worldwide R&D efforts are exploring the networking home projects in Korea and Japan flexibility provided by the new WDM dimension. An example is the 5-year, DARPA-led MoNET program References conducted by AT&T, Bellcore, Bell Atlantic, Bell 1 C. Fan and L. Clark, Opt. Photon. News, South, Lucent, PacTel, and other RBOCs. Their goal vol.6,pp26-32.(1995) was to explore the realization of a seamless, fully 2 N.S. Bergano, Optical Fiber Telecom IVB, p. 154 configurable, all-optical regional and national network 1. P. Kaminow and T Li eds, Academic(2002) infrastructure. Many new R&D programs have 3 H Kogelnik, Proc. ECOC 1996, paper MoA. 2.2 sprouted from MONET and its counterparts 4 H. Onaka, et al, Proc. OFC 1996, paper PD19 the design of scalable optical routers with throughput 6 T Morioka, et al, Proc. OFC 1996, paper PD, o example being the new IRIS program. This explores 5 A H. Gnauck, et al, Proc. OFC 1996, paper PD2 of more than 100 Tb/s using photonic integrated 7 K Fukuchi, et al, Proc. OFC 2001, paper PD24 circuits with a high level of integration and new 8 S Bigo, et al, Proc. OFC 2001, paper PD25 rchitectural ideas such as load balancing 9 R.C. Alferness, et al, in The Optics Encyclopedia pp2119-2135,Wey,(2004) 10 H. Kogelnik, IEEE J. Select. Topics in Quantum Conclusions and Outlook Electronics, vol 6, pp 1279-1286(2000) The R&D community in optical fiber communication 11 A. H. Gnauck, et al, Proc. OFC 2002, paper has achieved much in the past and advanced the FC-2 technological capabilities by orders of magnitude. It 12 AA M. Saleh, Proc. OFC 1996, paper Thl3 can be truly proud of these accomplishments. Many 13 M. Zimgibl, Stanford Workshop on Load Balancing challenges remain, including the extension of Mav.2004 broadband capabilities from the core network to the 14 H. Shinohara, Proc. OFC 2004, paper ThW2 Table1: Commercial Transmission Systems Wave. c Bit rate/ Bit ratel Voice System Year channels length channel spans FT3 1980082um 45 Mb/s 45 Mb/s 672 7 kr FT3C 1983082m 90 Mb/s90 Mb/s 13447km FTG417198513m1417Mbs417Mbs 604850km FTG-1.7 198713m 1.7Gb/s1.7Gb/s 2419250km FTG-1.7 WDM198Q.3/1. 21.7Gb/s3.4 Gb/s 48,38450km FT2000 199213m 2.5 Gb/s 2.5 Gb/s 3225650km FT2000WDM19921.3/155 2 2.5 Gb/s 5 Gb/s NGLN 1995155pm825Gbs20Gb/s 258.000 1997155um1625Gbs40Gb/s 516.000360km 1999155m 802.5Gb/s200Gb/s2.580000640km 10Gb/s|400Gb/ 20001.55 8010Gb800Gbs10,320000640km Wave Star 2001155m16010Gbs16Tb/s20640000640km 12810Gb/s128Tb/s16.5120004000km LambdaXtreme 2003 1.55 um 64 40 Gb/s 2.56 Tbls,024,000 1000 kn
point-to-point systems to multipoint metropolitan networks and to broadband access.9 The new ULH capabilities promise to enable all-optical networks. Worldwide R&D efforts are exploring the networking flexibility provided by the new WDM dimension. An example is the 5-year, DARPA-led MONET program conducted by AT&T, Bellcore, Bell Atlantic, Bell South, Lucent, PacTel, and other RBOCs. Their goal was to explore the realization of a seamless, fully configurable, all-optical regional and national network infrastructure.12 Many new R&D programs have sprouted from MONET and its counterparts, an example being the new IRIS program. This explores the design of scalable optical routers with throughput of more than 100 Tb/s using photonic integrated circuits with a high level of integration and new architectural ideas such as load balancing.13 Conclusions and Outlook The R&D community in optical fiber communication has achieved much in the past and advanced the technological capabilities by orders of magnitude. It can be truly proud of these accomplishments. Many challenges remain, including the extension of broadband capabilities from the core network to the end user. In this connection we will observe with great interest the evolution of new network architectures, the growth of 10-Gb Ethernet, and the fiber-to-thehome projects in Korea and Japan.14 References 1 C. Fan and L. Clark, Opt. & Photon. News, vol.6, pp 26-32, (1995). 2 N. S. Bergano, Optical Fiber Telecom IVB, p. 154 I. P. Kaminow and T. Li eds., Academic (2002). 3 H. Kogelnik, Proc. ECOC 1996, paper MoA.2.2 4 H. Onaka, et al, Proc. OFC 1996, paper PD19 5 A. H. Gnauck, et al, Proc. OFC 1996, paper PD20 6 T. Morioka, et al, Proc. OFC 1996, paper PD21 7 K. Fukuchi, et al, Proc. OFC 2001, paper PD24 8 S. Bigo, et al, Proc. OFC 2001, paper PD25 9 R.C. Alferness, et al, in The Optics Encyclopedia, pp 2119-2135, Wiley, (2004). 10 H. Kogelnik, IEEE J. Select. Topics in Quantum Electronics, vol. 6, pp 1279-1286 (2000). 11 A. H. Gnauck, et al, Proc. OFC 2002, paper FC-2. 12 A. A. M. Saleh, Proc. OFC 1996, paper ThI3. 13 M. Zirngibl, Stanford Workshop on Load Balancing May, 2004. 14 H. Shinohara, Proc. OFC 2004, paper ThW2. Table1: Commercial Transmission Systems System Year Wavelength WDM channels Bit rate/ channel Bit rate/ Fiber Voice channels per fiber Regen spans FT3 1980 0.82 µm 1 45 Mb/s 45 Mb/s 672 7 km FT3C 1983 0.82 µm 1 90 Mb/s 90 Mb/s 1,344 7 km FTG-417 1985 1.3 µm 1 417 Mb/s 417 Mb/s 6,048 50 km FTG-1.7 1987 1.3 µm 1 1.7 Gb/s 1.7 Gb/s 24,192 50 km FTG-1.7 WDM 1989 1.3/1.55 µm 2 1.7 Gb/s 3.4 Gb/s 48,384 50 km FT-2000 1992 1.3 µm 1 2.5 Gb/s 2.5 Gb/s 32,256 50 km FT-2000 WDM 1992 1.3/1.55 µm 2 2.5 Gb/s 5 Gb/s 64,120 50 km NGLN 1995 1.55 µm 8 2.5 Gb/s 20 Gb/s 258,000 360 km NGLN II 1997 1.55 µm 16 2.5 Gb/s 40 Gb/s 516,000 360 km WaveStarTM 400G 1999 1.55 µm 80 40 2.5 Gb/s 10 Gb/s 200 Gb/s 400 Gb/s 2,580,000 5,160,000 640 km 640 km WaveStarTM 800G 2000 1.55 µm 80 10 Gb/s 800 Gb/s 10,320,000 640 km WaveStarTM 1.6T 2001 1.55 µm 160 10 Gb/s 1.6 Tb/s 20,640,000 640 km LambdaXtreme 2003 1.55 µm 128 64 10 Gb/s 40 Gb/s 1.28 Tb/s 2.56 Tb/s 16,512,000 33,024,000 4000 km 1000 km