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Topic Name: 40 Gbps DQPSK
Category: STAR (Space, Telecommunications & Radioscience)
Research persons: Yokogawa's global network & Fujitsu IT and communications solutions
Location: 4-1-1 Kamikodanaka, Nakahara-ku,Kawasaki, Kanagawa 211-8588, Japan
Details
Yokogawa Electric Corporation and Fujitsu
Limited today announced the joint development of the world's first practical 40
Gbps optical transmission technologies using differential quadrature phase shift
keying (DQPSK)(1). The two companies are
respectively planning to incorporate the technologies in various new products
for 40 Gbps ultra high-speed optical transmission networks.
The new technologies were developed under the
strategic partnership established between Yokogawa and Fujitsu in March of 2006
to jointly develop core system technologies and key components for ultra
high-speed optical transmission systems, and with the cooperation of Fujitsu
Laboratories Ltd. Sample products were on display at the Optical Fiber
Communication Conference and Exposition (OFC) and the National Fiber Optic
Engineers Conference (NFOEC) 2007, held in Anaheim, California from March 27 -
29, 2007.
Background of Development
The dissemination of optical access networks
that directly connect households via optical fibers and the construction of next
generation networks have led to a increasing demand for greater capacity in
inter-city optical transmission networks. In order to meet this demand,
increasing the maximum transmission speed from 10 Gbps used in current optical
transmission systems to 40 Gbps is being considered.
Overview of Development
Challenge
Typically, when transmission speed is
increased, distortion caused by polarization mode dispersion (PMD)(2)
becomes pronounced, limiting transmission reach. For example, in the case of
transmission of a 40 Gbps signal using a standard binary modulation(3)
in an optic fiber that meets the PMD specification (0.2 ps /√km) recommended by
the ITU-T(4), transmission reach is limited
to a maximum of 100 km. Thus, inter-city transmission, which requires
long-distance transmission of more than several hundred kilometers, has not been
possible.
Seeking to overcome this obstacle, advances
are being made in investigating DQPSK-type transmission, which is tolerant to
waveform distortion due to PMD, and its high performance has been confirmed in
the laboratory experiments. However, the configuration of a DQPSK format is
complex, and thus large size and high power consumption of the optical
transceivers have proved to be challenges.
The Newly Developed
Technologies
Yokogawa Electric and Fujitsu Limited, in
cooperation with Fujitsu Laboratories Ltd, have successfully developed the
world's first practical 40 Gbps DQPSK optical transmission technologies:
1. DQPSK
LN Optical Modulator:
The LN optical modulator(5) for DQPSK
modulation, which was developed by Fujitsu and operates with the world's lowest
drive voltage, enables a compact optical transmission component design and lower
power consumption.
2.
Dedicated ICs and Devices that Enable DQPSK:
Compact, low power consumption dedicated ICs and other devices that enable DQPSK,
including a driver device optimized for the DQPSK LN optical modulator mentioned
above, optical / electrical conversion devices that operate stably despite PMD
waveform distortion, and clock and data recovery devices, were developed with
Yokogawa Electric's InP HBT(6) technology.
3.
Compact Optical Transmission Module:
Control technology was developed that allows the newly developed key devices to
operate in a stable manner as well as mounting technology that enables a compact
size, making possible a compact 110 mm x 320 mm x 40 mm package equipped with
all functions necessary for 40 Gbps DQPSK in the transmission equipment and a
low-power consumption of 35 W (with case temperature of 72°C).
Results
100 units of 40 Gbps DQPSK optical
transceivers were manufactured and transmission performance and stable operation
despite environmental changes, such as temperature fluctuations and variations
in supply voltages, was confirmed. Furthermore, the transmission reach as
limited by PMD was found to be approximately eight times better than that of
standard binary modulation (figure 2).
The resulting technology is expected to
significantly reduce the time it will take to implement major inter-city
high-capacity optical networks.
Moving Forward
Utilizing the newly developed technology,
Yokogawa Electric and Fujitsu are respectively planning to bring various
products for 40 Gbps ultra high-speed optical transmission networks to the
market.
Notes
- A modulation method for digital signals
whereby 2 bits of data are allocated to each of four modulated optical phases.
The use of four types of optical phases enables a pulse width that is double
that of the binary modulation scheme, reducing the effect of waveform distortion
due to PMD.
- Phenomenon in which light travels at
different speeds in the two polarization modes of an optical fiber causing
signal distortion at the optical receiver.
- A modulation method whereby the digital
singles "0" and "1" are assigned to either "bright" or "dark" optical signals,
or to "0°" or "180°" optical phases.
- An international organization that produces
standards in the telecommunications field.
- A device that converts an electrical data
signal into an optical data stream via the electro-optic effect of a LiNbO3
crystal. For more detailed information, please refer to the press release on
March 27, 2007.
- A compound semiconductor transistor with
outstanding high-speed performance and high drive capability with low IC power
consumption.
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- About Researcher Companies:
Yokogawa
Yokogawa's global network of 20 manufacturing
facilities, 80 companies, and more than 650 sales and engineering offices spans
31 countries. Since its founding in 1915, the US$4 billion company has been
engaged in cutting-edge research and innovation, securing more than 7,000
patents and registrations, including the world's first digital sensors for flow
and pressure measurement. Industrial automation and control, test and
measurement, information systems and industry support are the core businesses of
Yokogawa. For more information about Yokogawa, please visit our web site at
http://www.yokogawa.com.
Yokogawa Electric Corporation
Public Relations & Investor Relations
Tel: +81-422-52-5530
Fujitsu
Fujitsu is a leading provider of
customer-focused IT and communications solutions for the global marketplace.
Pace-setting device technologies, highly reliable computing and communications
products, and a worldwide corps of systems and services experts uniquely
position Fujitsu to deliver comprehensive solutions that open up infinite
possibilities for its customers' success. Headquartered in Tokyo, Fujitsu
Limited (TSE:6702) reported consolidated revenues of about 4.8 trillion yen
(US$40.6 billion) for the fiscal year ended March 31, 2006. See
http://www.fujitsu.com for further
information.
Fujitsu Limited
Public and Investor Relations
In pictures:
1.40 Gbps DQPSK optical transceiver
2.Comparison of 40 Gbps transmission range between binary modulation and DQPSK
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