IP: AT&T Announces Advances in Optical Technology

[Dave Farber <farber () cis upenn edu>]

While it is a press release it is interesting djf


> From: "Way, Karen, PR" <kway () att com>
> To: "'farber () cis upenn edu'" <farber () cis upenn edu>
> Subject: AT&T Announces Advances in Optical Technology
> Date: Mon, 6 Mar 2000 22:02:10 -0500
> X-Mailer: Internet Mail Service (5.5.2650.21)
>
> March 6, 2000
>
> David Farber
> University of Pennsylvania
>
> Dear David,
>
> Today AT&T issued four related releases describing recent breakthroughs in
> optical technology at AT&T Labs:
>
> o     Micromachines Offer Path Through Bottlenecks In Fiber Networks
>
> o     AT&T And LaserComm Team Up To Achieve A Major Breakthrough In
> Broadband Optical Transmission
>
> o     Researchers Design Pulse-Forming Silicon Chip For Use In Optical Nets
>
> o     Short Optical Pulses Go Long Distance For Data
>
> The full text of these releases is copied below.  If you have any questions
> or would like to speak with AT&T Labs researchers, please give me a call.
>
> Karen Way
> AT&T Industry Analyst Relations
> 908-221-6632 (work)
> 908-410-1847 (mobile)
> kway () att com
> ***********************************************
> MICROMACHINES OFFER PATH THROUGH BOTTLENECKS IN FIBER NETWORKS
>
> BALTIMORE -- AT&T researchers today announced that tiny, silicon-based
> micromachines may point the way towards clearing speed bottlenecks that
> constrain transmission capacity in older, installed optical fiber networks.
>
>
> The findings from AT&T Labs have significant implication for global carriers
> since a large portion of the world's long-haul communications infrastructure
> consists of fiber that was deployed a decade ago or longer.  This vintage
> fiber tends to cause polarization mode-dispersion (PMD), a fundamental
> effect that smears light pulses as they traverse a fiber -- limiting the
> ultimate speed at which information can be sent through it.
>
> AT&T researchers described a means by which lightwave micromachines (tiny
> movable optical circuits fabricated on silicon chips) can be used to undo
> the effects of polarization mode-dispersion.
>
> "As optical-transport systems move towards 10 to 40 Gbps speeds, it becomes
> increasingly important to develop technology that can compensate for PMD,"
> says Lih-Yuan Lin, senior research technical staff member at AT&T Labs in
> Red Bank, NJ.  "We have demonstrated a free-space micromachined polarization
> rotator and experimentally verified its action."
>
> This research holds the promise of using lightwave micromachines to build
> compact, low-cost polarization controllers that may ultimately remove
> PMD-related speed bottlenecks from the installed base of optical fiber
> networks.
>
> "Micromachines potentially occupy small volumes, they offer standard silicon
> economy, and the power required to operate them is only that needed to move
> tiny mirror slabs having sub-millimeter dimensions," Lin explains.  "The
> technology's promise appears to be substantial."
>
> AT&T researchers have demonstrated a micromachine-based polarization rotator
> (an essential building block of a PMD compensator) and proposed a path
> whereby a combination of such devices can be used to build a fully
> functional mechanism for removing the detrimental effects of PMD.
>
> The lightwave micromachines used in AT&T Labs' research consist of four tiny
> movable micromirrors -- two completely reflecting and two partially
> reflecting.  The micromirrors (each about the width of a human hair) are
> fabricated with integrated micro actuators that move the mirrors to change
> the phases of the reflected beams -- thus altering the polarization of light
> signals and potentially removing accumulated PMD.
>
> The micromirrors and associated actuators are batch fabricated on a tiny
> region (about five square millimeters) of a silicon chip using standard
> photolithographic techniques like those used to produce integrated
> electronic circuitry.
>
> "An individual optical fiber in today's state-of-the-art networks transports
> tens to hundreds of individual optical signals with each at a different
> color and modulated at multi-gigabit per second speeds," says Bob Tkach,
> head of Lightwave Networks Research at AT&T Labs.  "If a PMD-compensating
> device is to be practical, it must be compact, inexpensive and low in
> power-consumption.  All of that appears to be a real possibility with
> micromachines."
>
> AT&T Labs researchers will describe experimental results obtained with the
> polarization-controlling micromachine on Thursday afternoon, March 9th at
> the Optical Fiber Communications Conference in the Baltimore Convention
> Center.
>
> AT&T (http://www.att.com) is among the premier voice and data communications
> companies, serving more than 80 million customers, including consumers,
> businesses and government.  With annual revenues of more than $53 billion
> and 149,000 employees, AT&T provides services to customers worldwide. Backed
> by the research and development capabilities of AT&T Labs, the company runs
> the world's largest, most sophisticated communications network and has the
> largest digital wireless network in North America.  The company is a leading
> supplier of data and Internet services for businesses and offers
> outsourcing, consulting and networking-integration to large businesses.  It
> also has the nation's largest direct Internet access service for consumers.
>
> Through its recent cable acquisitions, AT&T will bring its bundle of
> broadband video, voice and data services to customers throughout the United
> States. Internationally, the AT&T/British Telecom Global Venture will serve
> the communications needs of multinational companies and international
> carriers worldwide.
>
> # # #
>
> AT&T AND LASERCOMM TEAM UP TO ACHIEVE A MAJOR
> BREAKTHROUGH IN BROADBAND OPTICAL TRANSMISSION
>
> BALTIMORE -- AT&T Labs, the research arm of AT&T [NYSE:T], and LaserComm
> Inc. today announced a breakthrough in developing next-generation
> high-bandwidth long-haul optical networks.  Using LaserComm's proprietary
> Hi-Mode Dispersion Management Device(tm) (DMD), the two companies were able
> to achieve 40 nm-wide wave division multiplexing (WDM) transmission of
> broadband 40 Gbps signals over a distance of 240km.
>
> Chromatic dispersion and dispersion slope - the tendency for light to spread
> out as it passes through a medium - are major obstacles in the
> implementation of next-generation broadband dense wave-division multiplexing
> (DWDM) systems transmission above 2.5 Gbps.  Today's solution, dispersion
> compensating fiber, cannot solve dispersion slope, leading to complicated
> and expensive trimming of individual channels.  LaserComm's Hi-Mode DMD uses
> a novel, elegant method of wideband dispersion compensation capable of
> correcting all wavelengths of light simultaneously with minimal loss and
> without exciting nonlinear effects.  The DMD's advantageous performance has
> been successfully validated in AT&T's advanced broadband 40Gbps transmission
> testing system.
>
> "Overcoming the limitations of dispersion and dispersion slope is critical
> for enabling broadband long-haul transmission," explained Bob Tkach,
> Division Manager of the Lightwave Networks Research department at AT&T Labs.
> "The performance of LaserComm's device was well above our expectations. This
> is the first device to provide full dispersion slope compensation on
> non-zero dispersion shifted fiber."
>
> In the experiment, eight laser sources from 1525nm to 1565nm, each modulated
> at 40 Gbps, were simultaneously transmitted through 240 km of non-zero
> dispersion shifted fiber (NZDSF) comprising three equal segments with
> in-line optical amplifiers. The unique aspect of this test was that a single
> Hi Mode DMD simultaneously compensated the different dispersions of all
> eight wavelengths for each segment.
>
> "We could not have validated the extent of our device's capabilities without
> AT&T's collaboration and their advanced testing system," says Dan Acton,
> President of LaserComm.  "Based on the outcome of this common effort we can
> now present the industry with the first ever broadband chromatic dispersion
> solution for 40 Gbps transmission."
>
> ABOUT AT&T LABS
>
> AT&T (http://www.att.com) is among the premier voice and data communications
> companies, serving more than 80 million customers, including consumers,
> businesses and government.  With annual revenues of more than $53 billion
> and 149,000 employees, AT&T provides services to customers worldwide. Backed
> by the research and development capabilities of AT&T Labs, the company runs
> the world's largest, most sophisticated communications network and has the
> largest digital wireless network in North America.  The company is a leading
> supplier of data and Internet services for businesses and offers
> outsourcing, consulting and networking-integration to large businesses.  It
> also has the nation's largest direct Internet access service for consumers.
> Through its recent cable acquisitions, AT&T will bring its bundle of
> broadband video, voice and data services to customers throughout the United
> States. Internationally, the AT&T/British Telecom Global Venture will serve
> the communications needs of multinational companies and international
> carriers worldwide.
>
> ABOUT LASERCOMM
>
> LaserComm, a privately held company, is a leader in developing photonic
> components for fiber optic networks. The Company was founded in 1998, with
> US headquarters in Plano, Texas and a research and development subsidiary in
> Tel Aviv, Israel. LaserComm recently closed a $15 million round of
> financing, speeding the Company's development of next-generation optical
> networking technology. LaserComm is constructing a manufacturing plant in
> Plano, Texas, where the Company will manufacture its own products. More
> information about LaserComm can be found at http://www.lasercomm-inc.com
>
> #  #  #
>
> RESEARCHERS DESIGN PULSE-FORMING SILICON CHIP FOR USE IN OPTICAL NETS
>
> 10 Gbps Networks Can Operate at Higher Bit Rates and Lower Costs
>
> BALTIMORE -- AT&T today announced that researchers have designed an optical
> transmitter that can cut costs and improve network reliability using a
> high-speed, electrical, nonlinear transmission line (NLTL) integrated
> circuit.
>
> AT&T Labs researchers have come up with a new technology that can achieve
> pulses in the 25-picosecond range using an all-silicon nonlinear
> transmission line integrated with a pulse-forming network.  Electronic
> signals that enter the chip are automatically reshaped into faster pulses
> that can be sent over high-speed networks.
>
> Instead of using a traditional Gallium Arsenide substrate, AT&T Labs
> researchers came up with an NLTL circuit that can be fabricated in large
> quantities on low-cost silicon substrates.
>
> "Through further integration of components and improved design, we should be
> able to operate at higher bit rates and shorter pulses," said Martin Birk,
> senior technical staff member at AT&T Labs.  "In the future, we could
> integrate the pulse source, electrical modulation and other electrical
> components to significantly reduce transmitter complexity, cut costs and
> improve reliability."
>
> Researchers were able to show the feasibility of using an all-silicon NLTL
> in a transmission system at 10 Gbps data rates.  The results indicated a
> 1.5decibel gain in receiver sensitivity for return-to-zero (RZ) over
> non-return-to-zero (NRZ) data formats.
>
> The findings will be presented on at the Optical Fiber Communication
> Conference at 4:30 p.m. on Tuesday, March 7th in Room 321/323 of the
> Baltimore Convention Center.
>
> AT&T (http://www.att.com) is among the premier voice and data communications
> companies, serving more than 80 million customers, including consumers,
> businesses and government.  With annual revenues of more than $53 billion
> and 149,000 employees, AT&T provides services to customers worldwide. Backed
> by the research and development capabilities of AT&T Labs, the company runs
> the world's largest, most sophisticated communications network and has the
> largest digital wireless network in North America.  The company is a leading
> supplier of data and Internet services for businesses and offers
> outsourcing, consulting and networking-integration to large businesses.  It
> also has the nation's largest direct Internet access service for consumers.
> Through its recent cable acquisitions, AT&T will bring its bundle of
> broadband video, voice and data services to customers throughout the United
> States. Internationally, the AT&T/British Telecom Global Venture will serve
> the communications needs of multinational companies and international
> carriers worldwide.
>
> # # #
>
>
> SHORT OPTICAL PULSES GO LONG DISTANCE FOR DATA
>
> Spectral Efficiency of 18% Achieved Using Highly Dispersed Pulses
>
> BALTIMORE -- AT&T today announced that researchers at AT&T Labs have
> narrowed the spacing between channels in pulse-based 40 Gbps Wave Division
> Multiplexing (WDM) networks down to 1.8 nanometers without excessive signal
> degradation.
>
> This advance promises that high-bit-rate systems can operate over long
> distances with spectral efficiency comparable to 10 Gbps systems, allowing
> full use of the data handling capability of the fiber.
>
> The researchers used highly dispersed pulses to carry signals at 40 Gbps
> over 800 kilometers of conventional single-mode fiber (SMF) with optical
> amplifiers situated every 80 kilometers.
>
> "This research shows that it's possible to operate fiber links at very high
> channel rates with many wavelength channels, by using short optical pulses
> to carry data, so as to efficiently use the full bandwidth provided by
> optical fibers" says Sang-Gyu Park, senior technical staff member at AT&T
> Labs.
>
> In this study, researchers used short (2.5 to 3.7 picosecond) broad-spectrum
> pulses that rapidly disperse in the fiber link.  Instead of applying
> sophisticated dispersion management techniques to limit pulse distortion, no
> effort was made to compensate for distortion until the pulse reached its
> destination at 800 km.
>
> "Because the broad-spectrum pulses propagate without significant nonlinear
> effects, the location of dispersion compensating elements is not critical,"
> says Park.  "In our experiments, all dispersion compensation is performed at
> the end of the 800-km link.  Moreover, our computer simulations show that
> periodic dispersion compensation is slightly deleterious because re-forming
> the pulses allows the nonlinearity to act briefly on pulse transitions."
>
> The findings will be presented on at the Optical Fiber Communication
> Conference at 2:45 p.m. on Tuesday, March 7th in Room 316/317 of the
> Baltimore Convention Center.
>
> AT&T (http://www.att.com) is among the premier voice and data communications
> companies, serving more than 80 million customers, including consumers,
> businesses and government.  With annual revenues of more than $53 billion
> and 149,000 employees, AT&T provides services to customers worldwide. Backed
> by the research and development capabilities of AT&T Labs, the company runs
> the world's largest, most sophisticated communications network and has the
> largest digital wireless network in North America.  The company is a leading
> supplier of data and Internet services for businesses and offers
> outsourcing, consulting and networking-integration to large businesses.  It
> also has the nation's largest direct Internet access service for consumers.
> Through its recent cable acquisitions, AT&T will bring its bundle of
> broadband video, voice and data services to customers throughout the United
> States. Internationally, the AT&T/British Telecom Global Venture will serve
> the communications needs of multinational companies and international
> carriers worldwide.
>
> # # #