Fujitsu Introduces World's Most Compact Integrated DQPSK Receiver for 40Gbps Optical Networks

January 07, 2010

- PLC technology realizes the world's most compact size -

In recent years, the global expansion of new services such as cloud computing and on-line streaming has brought about a dramatic increase in data communications. As the data transmission volume of communications networks rises, optical transmission equipment for 40Gbps backbone networks is being widely introduced. However, due to advances in transmission speed, the components that constitute these optical transmission equipments are growing both in size and complexity. Larger equipment results in the need for larger installation space. Meeting the demands of growing data communications while reducing environmental impact at the same time has become a major challenge for 40Gbps systems.

Until recently, generating digital signals of 1 and 0 by turning a light on and off had been the common method of intensity modulation for optical networks. However, responding to the growing needs for ultra-high-speed and long-distance transmission, phase modulation has become the mainstream modulation method for 40Gbps optical networks. Phase modulation generates digital signals of 1 and 0 by changing the phase of light while allowing it to be in the ON position.

DQPSK, one of the phase modulation formats, transmits 2 bits per symbol using four phases, thus increasing the spectral efficiency, and provides enhanced tolerance to both chromatic and polarization mode dispersions. In addition, DQPSK reduces the operating bandwidth of optical and electrical peripheral components that are used in 40Gbps optical transponders and/or transmission systems. However, there exists technical issues to overcome since the DQPSK optical modulator and receiver becomes bigger and complicated in structure.

Fujitsu Optical Components has succeeded in commercializing the most compact Integrated 40Gbps DQPSK Receiver. This receiver is used for 40Gbps optical transponders capable of handling DQPSK allowing the transponders to become more compact and lower cost.

Key Technology

1. Compact single chip optical circuit by PLC technology
DQPSK receiver module requires two delay line interferometers, therefore, the module's size constraints become more obvious and the complexity of optical coupling increases, which makes it a challenging task to install a lot of optical elements by conventional method using free-space optics. Fujitsu Optical Components ("FOC") has overcome the technical difficulties by integrating the two delay line interferometers into a single compact chip by the PLC technology. Moreover, the PLC technology can reduce the manufacturing cost because PLC is manufactured by using the semiconductor wafer processes.

2. Integration of PLC chip, photo detector and amplifier in a single seal package
DQSPK receiver module requires integrating the PLC chip and the photo detectors with high efficiency optical coupling. To achieve the high efficiency optical coupling, the waveguide design of PLC chip is optimized and the elements are precisely mounted by micro-assembly technology. Hermetically sealed package is also used to achieve the high reliability. FOC applies the optimized high-speed circuit design and stable mass-production technology, which is already being used for FOC's existing products.

3. User-friendly interface
All DC terminals are located on both side wall separately from RF signal terminals. By integrating RF signal terminals on one flexible print circuit (FPC), enhanced connection and circuit board arrangements, as well as simplified working processes and manufacturing cost reductions, are achieved.

Pricing & Availability

Sales Target

• 500 million yen in fiscal 2010
• 1 billion yen in fiscal 2011

Additional Information

http://www.fujitsu.com/jp/foc/en/

Glossary & Notes

(*1) As of December, 2009, our company's examination, excluding the projection parts such as terminals

(*2) DQPSK
Acronym for Differential Quadrature Phase Shift Keying. It is a method of phase modulation for digital signals, in which 2 bits of data are allocated to each of 4 modulated optical phases (0°, 90°, 180° and 270°).

(*3) Balanced Receiver
Consisting of two photodiodes that receive both positive optical phase and reverse optical phase output from delay line interferometers, it improves receiving characteristics by using the difference of those photodiode currents.

(*4) Delay Line Interferometer
A component that converts phase modulation to intensity modulation. In the case of DQPSK, the light modulated on phase is divided in two optical paths with half strength, and after one side is delayed for the time corresponding to about one bit, these two lights are combined to one light and interfered.

(*5) PLC
Acronym for Planar Lightwave Circuit. Optical circuit chip that forms waveguide that propagates light with accuracy exceeding optical wavelength order on silicon or quartz substrate.

(*6) Transponder
A module with the function to convert light signals and electrical signals, as well as MUX/DEMUX. It is used as an interface for the optical transmission line of optical transmission devices.

Press Contacts

Fujitsu Limited
Public and Investor Relations Division
Website: https://www-s.fujitsu.com/global/news/contacts/inquiries/index.html

Customer Contacts

Fujitsu Optical Components Limited
Sales & Business Development Division
Marketing & Business Development Dept.
 E-mail: optmdl-pr@ml.css.fujitsu.com

About Fujitsu

Fujitsu is a leading provider of IT-based business solutions for the global marketplace. With approximately 175,000 employees supporting customers in 70 countries, Fujitsu combines a worldwide corps of systems and services experts with highly reliable computing and communications products and advanced microelectronics to deliver added value to customers. Headquartered in Tokyo, Fujitsu Limited (TSE : 6702) reported consolidated revenues of 4.6 trillion yen (US$47 billion) for the fiscal year ended March 31, 2009. For more information, please see: www.fujitsu.com.

About Fujitsu Optical Components

Aiming to strengthen Fujitsu's optical module business, Fujitsu Optical Components was established on April 1st, 2009 as a wholly owned subsidiary of Fujitsu Limited. With the establishment of the new company, the sales, research and development, and manufacturing functions of Fujitsu's optical module business are integrated under a unified management structure. Headquartered in Kawasaki, Japan, Fujitsu Optical Components is a leading supplier of the most advanced, high-reliable and customer-focused optical components for datacom and telecommunications applications in the global market. Its broad products line-up includes DWDM pluggable transceivers, full-band tunable 300pin transponders, G-PON transceivers and 40G/100G LN modulators. The company also plans to provide the most advanced 40G/100G integrated receivers in the near future. For additional information, visit http://www.fujitsu.com/jp/foc/en/.

All other company or product names mentioned herein are trademarks or registered trademarks of their respective owners. Information provided in this press release is accurate at time of publication and is subject to change without advance notice.