Combined OFC/NFOEC glances back and focuses forward

Three technologies, developed three and a half decades ago, seeded the ongoing development of fiber to the home today.

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Three technologies, developed three and a half decades ago, seeded the ongoing development of fiber to the home today.

The Optical Fiber Communication Conference (OFCC) began in 1975, as a scientific conference sponsored by the IEEE Communications Society and the IEEE Lasers and Electro-Optics Society (LEOS). The National Fiber Optics Engineers Conference (NFOEC) began a decade later as an optical-technology meeting sponsored by Bellcore (now Telcordia) and the newly formed Regional Bell Operating Companies (RBOCs). Reflecting industry consolidation in the wake of the recent boom and bust cycle, the two meetings will be held together for the first time next month as OFC/NFOEC, March 6-11 in Anaheim, CA. Perhaps appropriately, the two OFC plenary talks on Tuesday, March 8, at 8 a.m., will embrace themes of glancing backward as well as focusing forward.

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FIGURE 1. On Tuesday, engineers will describe a DWDM large-scale-PIC transmitter architecture in which each transmit channel consists of a tunable DFB laser with an integrated back-facet power monitor, an electro-absorption modulator, and a variable optical attenuator (VOA), used mainly for power flattening.
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Donald Keck, retired vice president and research director at Corning (Corning, NY) will glance backward three and a half decades at the first Internet experiments, first room-temperature semiconductor laser demonstration, and the invention of low-loss optical fiber that came together to ultimately produce an optical telecom industry. The other plenary speaker, Hiromichi Shinohara, director of NTT Access Network Service Systems Labs (Kanagawa, Japan) will focus forward on fiber to the home (FTTH): a rapidly growing market in Japan, a primary goal for the telecommunications industry worldwide, and a well-represented topic among technical presentations at the meeting.

Tuesday highlights

During Tuesday’s technical sessions, engineers from Infinera (Sunnyvale, CA) will herald the arrival of affordable, high-speed and high-bandwidth photonic integrated circuitry (PIC) in the form of an indium phosphide-based, 10-channel transmitter and receiver dense wavelength-division-multiplexing (DWDM) PIC pair capable of transmitting and receiving data at 40 Gbit/s per channel for an aggregate data communication rate of 400 Gbit/s (paper OTuM2; see Fig. 1). In the following talk, researchers from the University of California-Santa Barbara, will offer a possible replacement for distributed-feedback (DFB) lasers in WDM systems, in networks requiring dynamic provisioning, in phased radar systems, and in optical switching and routing, in the form of a monolithically integrated widely tunable transmitter using a series push-pull Mach-Zehnder electrode structure with a semiconductor optical amplifier and SGDBR laser suitable for 40-Gbit/s systems with tuning over 34 nm (paper OTuM3).

Also on Tuesday, engineers from Therma-Wave (Fremont, CA) and the University of Arizona (Tucson) will discuss fiber-bundle preparation methods for high-power applications (paper OTuF6). Researchers from the University of Tokyo will describe unrepeated transmission of 20‑Gbit/s quadrature phase-shift-keying (QPSK) modulation format ­signals over 210 km using coherent detection and digital signal processing (paper OTuL4). Corning engineers will describe the fabrication and characterization of hollow-core photonic-bandgap fiber fabricated with group birefringence of 0.025 at 1550 nm (paper OTuI1). Researchers from Ghent University (Ghent, Belgium) will discuss the use of divisible load theory to examine operational costs when connecting different sites of a computational grid in an optical-transport network (paper OTuP1); and engineers from MCI (Richardson, TX), Ciena (Linthicum, MD), and Mintera (Lowell, MA) will describe transmission of a 40-Gbit/s optical signal on a 1200-km ultra-long-haul, multispan, mixed-field fiber route from Sacramento, CA, to Salt Lake City, UT (paper OTuH4).

Wednesday highlights

On Wednesday, March 9, NTT researchers will describe the steps they have taken and continue to take as FTTH installations double from about 500,000 connections in the summer of 2004 to more than 1 million in the summer of 2005 (paper OWP2). Strategies they have implemented to reduce costs of bringing optical cables into subscriber’s homes to nearly the same cost level as for metallic lines include collocating optical fiber with metallic cabling to save space, and using fiber-reinforced plastics to provide drop-fiber tension without a need for grounding (see Fig. 2). They will also describe additional cost-cutting steps, such as the introduction of outer clasp connectors and bendable optical cable. Because video delivery is the dominant high-bandwidth application for FTTP networks, engineers from Harmonic (Sunnyvale, CA) will offer cost models, as well as qualitative comparisons, in the same session to advocate the economic advantages of a hybrid video architecture that uses RF for broadcast video and switched IP for targeted video (paper OWP4).

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FIGURE 2. Efficiency measures to be described on Wednesday, such as collocating optical fiber with metallic cabling in the external termination box and using fiber reinforced plastics to provide drop-fiber tension without a need for grounding (left) have enabled NTT engineers to achieve a 20% cost reduction from 2002 to 2004 in FTTH deployments. And additional modifications in connector design and optical cable flexibility are expected to bring fiber installation costs on par with metallic wire installation costs (right).

Also on Wednesday, Engineers from Bell Labs (Holmdel, NJ) and from the Fraunhofer Institute (Berlin, Germany) will discuss innovative techniques for sampling optical signals (papers OWJ1 and OWJ6). Engineers from Telcordia (Red Bank, NJ), the Laboratory for Telecommunication Sciences (Adelphi, MD) and Los Alamos National Laboratory (Los Alamos, NM) will describe multiplexing and transmission of a 1.3-µm quantum-key distribution system over a 1.5-µm metropolitan- area DWDM system (paper OWI2). NTT engineers will describe stable transmission of a 10-Gbit/s optical signal over a 1-km length of legacy multi­mode fibers using mode-limiting and incoherent light sources (paper OWH3). Researchers from Tohoku University (Sendai, Japan) describe fabrication of Silica-core Bragg fibers with a diameter below 10 µm to achieve single-mode transmission (paper OWL5). Engineers from StrataLight Communications (Campbell, CA) will describe development of a silicon germanium equalizer integrated circuit to mitigate fiber-induced and electro-optical distortions in 40-Gbits/s optical transmission (paper OWO2). NTT engineers will describe their achievement of more than 1000-channel, 6.25-GHz-spaced ­ultra-DWDM transmission using a supercontinuum multicarrier source (paper OWA6). And researchers from the Royal Institute of Technology (Kista, Sweden), Zhejiang University (Hangzhou, China), Optillion (Stockholm, Sweden) and SHF Communication Technologies (Berlin, Germany) describe 80-Gbit/s non-return-to-zero data transmission using an electrical time-­division-multiplexing fiber optic transmitter based on a segmented traveling-wave electro-absorption modulator (OWE1).

Thursday highlights

In the first of two back-to-back presentations on Thursday, March 10, one group of NTT engineers will describe flexible, low-loss interconnection of waveguides in three-dimensional planar lightwave circuits (PLCs), enabled by near-IR femto­second laser-writing techniques (paper OThV1; see Fig. 3). Another group will describe the use of a wavefront-matching method to optimize refractive-index distribution while minimizing the need for arduous calculations in fabricating a compact wavelength splitter (­paper OThV2). In a different session on nonlinear fibers and effects, researchers from Asahi Glass (Yokohama, Japan) and the University of Tokyo will describe development of an erbium-doped bismuth oxide-based nonlinear optical fiber to reduce propagation loss (paper OThA1). And University of Southampton researchers will report on fabrication of high-index-core one-dimensional micro­structured optical fiber with high-index-contrast layers (paper OThA5).

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FIGURE 3. In near-IR femtosecond laser writing of 3-D PLC waveguides to be described on Thursday, the two waveguide ends were separated by 2000 µm before interconnection and the bending radius of the written waveguide was estimated to be about 22 mm.
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In addition, researchers from University College London and Intel Research (Cambridge, England) will discuss electronic dispersion compensation by signal predistortion using a dual-drive Mach-Zehnder ­modulator (­paper OThJ2). Engineers from Xponent Photonics (­Monravia, CA) will discuss fabrication and testing of PLC triplexers (­paper OThU7). Researchers at the University of ­California-­Berkeley and the Technical University of Munich (­Germany) will report on enhancement of the resonance frequency of 1550‑nm VCSELs from 7 GHz up to almost 50 GHz using an optical injection-locking technique (paper OThM2). And University of Arizona (Tucson) researchers will present an innovative approach based on ternary modulation codes for suppressing intrachannel nonlinear effects in high-speed optical transmission (paper OThJ2).

Friday highlights

On Friday, March 11, researchers from the Fraunhofer Institute will report on achieving 80- and 160-Gbit/s data rates using a PIN photodetector module having 0.63-A/W responsivity at 1.55 µm and 85-GHz bandwidth (paper OFM1). NTT engineers will return to the topic of cost cutting for increasing FTTH deployment, this time using a fiber-handling robot to reduce both operational and equipment costs in construction of intelligent buildings and optical access networks (paper OFP5; see Fig. 4).

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FIGURE 4. To improve on the reliability while cutting cost and time involved in manual crossconnection of optical cabling systems, NTT engineers have developed an automated system for connecting up to 200 input optical fibers to 200 output fibers, which will be described on Friday. A personal computer remotely controls and manages the system, which in addition to the optical connection device includes a fiber-handling robot and an optical-fiber storage cartridge.
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The conference will also include an NFOEC technical program; a three-day Market Watch program of business, management, and technology topics; interactive NFOEC panel discussions on topics ranging from network planning and architecture, to devices, components, and equipment; and short courses starting on Sunday, March 6, and running through, Wednesday, March 9. In addition, more than 600 exhibitors are expected to participate in the trade show from March 8-10.

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