Fujitsu Develops 40Gbps Optical Transmitter Module, Heralding Next
Wave in High-Speed Optical Communications Systems
Tokyo, January 16, 2002 -- Fujitsu Limited announced today that it has
developed a 40-gigabit per second optical transmitter module, a major
milestone in creating the next generation of high-speed optical
communications systems. The company will now focus on commercializing
the module and plans to begin shipping samples in March of this year.
As broadband Internet becomes more widely available, transmission
volumes are expected to increase at a faster pace than ever. To help
cope with these communication volumes, engineers around the world are
pursuing the development of high-speed, high-capacity next generation
optical communications systems in such technology areas as DWDM.
In developing its new 40Gbps optical transmitter module, Fujitsu took
advantage of its own ultra high-speed optical devices and electronic
circuit technology, including its LiNbO3 (LN) Mach-Zehnder optical
external modulator and double heterostructure HEMT MMIC. By eliminating
the need to incorporate separate 40Gbps high-speed circuitry or complex
control circuitry, Fujitsu's module will help speed the development of
40Gbps optical transmission systems.
Prototypes of the new module will be demonstrated at the 2nd Fiber
Optics Expo starting January 16 at the Tokyo International Exhibition
Center (Tokyo Big Site).
[About the 40Gbps Optical Transmitter Module]
A key challenge in realizing a 40Gbps optical transmission system
has been developing an optical transmitter module (E/O) that can
convert 40Gbps electrical signals into optical signals and transmit
them. One problem has been the waveform distortions that occur when
transmitting optical signals over fiber-optic cable for long distances.
This problem has given rise to the need for characteristics (called
dispersion-tolerant characteristics) that can control the wavelength
deviations that cause distortions in the waveform.
Fujitsu was able to overcome these obstacles by employing its renowned
optical device and electronic circuit technology, including the Mach-
Zehnder LN optical external modulator, a four wave tunable LD module
with wavelength locker, LN driver circuit, and control circuit block.
Moreover, because the optical transmitter is in module form, customers
need not worry about designing hard-to-handle 40Gbps high-speed
circuitry and complex control circuitry, thereby accelerating the
various testing processes and system development.
[Features of the 40Gbps Optical Transmitter Module]
* All company/product names mentioned may be trademarks or registered
trademarks of their respective holders and are used for identification
- LN Optical Modulator
The Mach-Zehnder LN optical external modulator offers excellent
dispersion-tolerant characteristics and high-speed optical
modulation characteristics over a wide bandwidth to transmit
optical signals over long distances. The lithium niobate (LiNbO3)
optical crystal has the property of changing the phase of lightwave
when voltage is applied. This phase change can be used to switch
the optical signal on or off, and makes for a faster electrical-
optical conversion process. This optical modulator has excellent
modulation properties, including a pulse reshaping effect, and,
because the modulation spectrum (wavelength deviation) is narrow,
it offers superior fiber transmission characteristics.
- Four Wave Tunable LD Module with Wavelength Locker
As an optical source, the module incorporates a tunable LD module
with wavelength locker that offers precise wavelength control,
permitting any one of four ITU-standard 100GHz consecutively spaced
wavelengths to be selected. A semiconductor laser module with a
precisely tuned wavelength and stable output, this device varies
the wavelength by changing the laser temperature. Because one
device tunes four wavelengths-worth of light output, optical
communications systems can be built with fewer spare devices.
- Wideband, High-Output LN Driver Circuit
While the LN optical modulator has excellent modulation and fiber-
transmission characteristics, it requires a relatively high voltage
of 5V. Developing a suitable ultra-high-speed, high-output
modulator driver circuit was therefore a key technological
challenge. Fujitsu was able to meet this challenge with an
ultrawide-bandwidth distributed amplifier circuit using a double-
heterostructure HEMT MMIC.
HEMTs are field-effect transistors that take advantage of the fact
that electrodes created from the hetero-interface of different
kinds of semiconductor material (such as GaAs and AlGaAs) operate
at higher speeds than those within conventional silicon (Si)
semiconductors. Fujitsu pioneered the development of these devices
in 1980, and today they are used in nearly all satellite
transceivers. Gate sensitivity is shorter, and, to ensure adequate
gain and output voltage at high frequencies, a double heterostructure
- Control circuit block
It includes an automatic bias control circuit which enables the LN
optical modulator to run reliably for at least 20 years, a four wave
tunable LD frequency-selection circuit, and a precision oscillator
control circuit, making the module especially easy to use.
Fujitsu is a leading provider of Internet-focused information technology
solutions for the global marketplace. Its pace-setting technologies,
best-in-class computing and telecommunications platforms, and worldwide
corps of systems and services experts make it uniquely positioned to
unleash the infinite possibilities of the Internet to help its customers
succeed. Headquartered in Tokyo, Fujitsu Limited (TSE:6702) reported
consolidated revenues of 5.48 trillion yen for the fiscal year ended
March 31, 2001. Internet: http://www.fujitsu.com/
Takehiro Hayashi, Scott Ikeda
Fujitsu Limited, Public Relations
Tel: +81-3-3215-5259 (Tokyo)
OEM Promotion Department
Photonic Technology Dev. Div.
Tel: +81-44-754-3087 (Kawasaki)
understand that product prices, specifications and other details are
current on the day of issue of the press release, however, may change
thereafter without notice.