- Intended for data communications in next-generation servers using optical
interconnects -
Kawasaki, Japan, May 31, 2012 - Fujitsu Laboratories Limited today announced
the development of a compact, cost-effective optical transceiver, a necessary
step toward developing optical interconnects for high-speed, high-bandwidth
data transmission among CPUs in the next generation of servers.
The data rate and space available for mounting the optical transceivers in use
today are obstacles in the way of making future high-performance servers a
reality. Fujitsu Laboratories therefore achieved improvements on the driver
IC circuit and module packaging structures, enabling transfer speeds of 25
Gbps over each channel in next-generation interconnects, a necessary step
toward doubling conventional transmission rates.
This technology enables high-speed, high-bandwidth data communications among
CPUs in a server, and between CPUs and peripheral devices. This also marks a
significant step toward the improved performance that future supercomputers
and high-performance servers will demand.
Details of this technology will be presented at the IEEE 62nd Electronic
Components and Technology Conference to be held in San Diego, California on
May 29.
<Background>
Advances in CPU processing power have greatly increased the data-processing
capabilities of servers. Now, with improved virtualization technology which
allows a single CPU to run multiple processes, the volume of data passing
among CPUs and between CPUs and peripherals is vastly increasing. While
today's servers use optical interconnects capable of data rates of 10 Gbps
per channel, expectations for future servers are that they will be able to
run even faster, at 25 Gbps. Furthermore, as Figure 1 illustrates, it is also
hoped that optical interconnects can be used not only for data communications
among servers, but also among boards within a server, as higher data rates
become difficult to achieve with electrical communications.
<Technological Issues>
Implementing optical interconnects within a server requires an optical
transceiver that converts electrical signals into optical signals. Current
optical transceivers have reached data rates between 10 and 14 Gbps, so the
speed of optical transceivers themselves has become a barrier to achieving
hoped-for data rates of 25 Gbps. Furthermore, current optical transceivers
are physically bulky, making them difficult to place near CPUs or other
devices. This is problematic because the electrical signal traveling between
the device and optical transceiver encounters line transmission losses and
interference that increases with the length of the electrical circuit. This
degrades signal quality and makes it more difficult to increase speeds.
<Newly Developed Transceiver>
In order to succeed in producing a compact optical transceiver with the
optical interconnects necessary for high-speed, high-bandwidth data
transmissions inside servers, Fujitsu Laboratories has developed an
opto-electric converter to turn electrical (optical) signals into optical
(electrical) signals through an optical device. Details of the technologies
follow.
1. High-speed circuitry technology
Fujitsu Laboratories was able to increase speeds through circuit technology
in the IC circuit that runs optical devices by making waveforms of optical
signals rise and fall more steeply even in inexpensive optical devices with
insufficiently fast response times, and by installing circuit technology
that suppresses multiple reflections that degrade the electrical signal's
waveform. This resulted in an increase in data rates from the current 10-14
Gbps to 25 Gbps per channel.
2. Compact Optical Coupling Technology
Conventionally, efficiently transmitting optical signals between
opto-electric converters and optical fiber (optical coupling) required an
optical coupling unit that consisted of a lens component and an optical
connector (Figure 3). However, the size of the lens component was large and
the cost was high. This new construction consists of an opto-electric
converter with a flexible printed circuit board that has been equipped with
optical devices and ICs, allowing for a compact optical transceiver. In
addition, Fujitsu Laboratories has also developed a cost-effective film-type
lens sheet which is stacked on the underside of the flexible printed circuit
board, thereby solving the problems mentioned above.
These technologies were used on a prototype of a 4ch x 25 Gbps opto-electric
converter. With a size of 22 mm x 9 mm x 0.86 mm (including on-board
electrical components and optical waveguide), the lens component is less than
one-tenth as large as conventional lens components in opto-electric converters,
while the overall unit has been slimmed down to one-third the conventional
size. Taking advantage of its thin size, Fujitsu Laboratories developed
optical transceivers with the prototype opto-electric converters placed on
the both side. Transmitters and receivers both utilize eight channels with a
compact size of 47.8 mm x 16 mm x 21.6 mm, enabling adjacent devices such as
the CPU on the printed circuit board to occupy a smaller area.
<Results>
These technologies achieve 25 Gbps per channel compactly and cost-effectively,
the capacity required for next-generation interconnects. This paves the way
for high-speed, high-bandwidth communications in servers.
<Future Plans>
Fujitsu Laboratories is proceeding with research and development to apply this
technology to high-performance servers, with the goal of practical use in
servers within three years. It also plans to extend this technology more
widely to increase the performance of information and communications equipment.
<About Fujitsu>
Fujitsu is the leading Japanese information and communication technology (ICT)
company offering a full range of technology products, solutions and services.
Over 170,000 Fujitsu people support customers in more than 100 countries. We
use our experience and the power of ICT to shape the future of society with
our customers. Fujitsu Limited (TSE:6702) reported consolidated revenues of
4.5 trillion yen (US$54 billion) for the fiscal year ended March 31, 2012.
For more information, please see http://www.fujitsu.com.
<About Fujitsu Laboratories>
Founded in 1968 as a wholly owned subsidiary of Fujitsu Limited, Fujitsu
Laboratories Limited is one of the premier research centers in the world.
With a global network of laboratories in Japan, China, the United States and
Europe, the organization conducts a wide range of basic and applied research
in the areas of Next-generation Services, Computer Servers, Networks,
Electronic Devices and Advanced Materials. For more information, please see:
http://jp.fujitsu.com/labs/en.
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