+44 (0)24 7671 8970
More publications     •     Advertise with us     •     Contact us
 
News Article

Fujitsu develops 40 Gbit/s optical transmitter module

Tokyo, Japan. Fujitsu Limited has developed a 40 Gbit/s 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.

In developing its new 40 Gbit/s optical transmitter module, Fujitsu took advantage of its own ultra high-speed optical devices and electronic circuit technology, including its lithium niobate (LN) Mach-Zehnder optical external modulator and double heterostructure GaAs HEMT MMIC. By eliminating the need to incorporate separate 40 Gbit/s high-speed circuitry or complex control circuitry, Fujitsu s module will help speed the development of 40 Gbit/s optical transmission systems.

A key challenge in realizing a 40 Gbit/s optical transmission system has been developing an optical transmitter module (E/O) that can convert 40 Gbit/s 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, modulator driver circuit, and control circuit block. Moreover, because the optical transmitter is in module form, customers need not worry about designing hard-to-handle 40 Gbit/s high-speed circuitry and complex control circuitry, thereby accelerating the various testing processes and system development.

Features of the 40 Gbit/s optical transmitter module

Lithium niobate 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 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 modualtor 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.

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. Takehiro Hayashi, Scott Ikeda
Fujitsu Limited, Public Relations
Tel: +81-3-3215-5259 (Tokyo)
Fax: +81-3-3216-9365
E-mail: pr@fujitsu.com
Web site: http://www.fujitsu.com

×
Search the news archive

To close this popup you can press escape or click the close icon.
×
Logo
×
Register - Step 1

You may choose to subscribe to the Compound Semiconductor Magazine, the Compound Semiconductor Newsletter, or both. You may also request additional information if required, before submitting your application.


Please subscribe me to:

 

You chose the industry type of "Other"

Please enter the industry that you work in:
Please enter the industry that you work in: