Skip to main content



Archived content

NOTE: this is an archived page and the content is likely to be out of date.

Fujitsu To Release the World's Lowest Drive Voltage (4.0v) DQPSK LN Optical Modulator for 40 Gbps Optical Transmission Systems

Fujitsu Limited

Tokyo, March 27, 2007

Fujitsu Limited today announced the development of the world's lowest drive voltage DQPSK(1)LN optical modulator(2) for 40 Gbps optical transmission systems. The product, which will make possible the construction of commercial systems with greater reliability, low power consumption and superior transmission quality, will be available June 1, 2007.

Figure 1:DQPSK LN Optical Modulator

Larger View (69 KB)

40 Gbps core optical network systems are being increasingly deployed in response to dramatic increases in data transmission traffic brought about by the global expansion of broadband networks. While many optical transmission signal encoding methods are under consideration, DQPSK transmission technology is becoming essential due to its strength against signal distortions resulting from transmission fibers and relay nodes, as well as its superior bandwidth efficiency.

There has been growing demand for low drive voltage and broadband optical modulators required for the construction of commercial optical transmission systems. However, achieving both low drive voltage and broadband capabilities has been a major challenge for DQPSK compatible modulators, due in part to their complicated structures.

Now, Fujitsu Limited and Fujitsu Laboratories Ltd. have jointly developed technology to overcome this challenge, and Fujitsu will begin sales of a DQPSK low drive voltage LN modulator for commercial optical transmission systems.

Key Features

1. Ultra Low 4.0 V Drive Voltage

Conventional LN modulators have required 20 Gbps high-speed electric signals of 10 V or higher in order to generate 40 Gbps DQPSK signals, and reducing the size and power consumption of drive circuits while maintaining reliability has been a challenge.

Fujitsu's new LN modulator achieves a drive voltage of 4.0 V, the lowest in the world, making it a practical optical modulator for use in commercial systems.

2. High-Quality DQPSK Signal Generation

In order to generate high-quality DQPSK signals, it is necessary to expand the bandwidth of optical frequency response. Using technology similar to that employed in previously commercialized 40 Gbps LN moderators, a 25 GHz bandwidth has been achieved.

3. User-friendly Interface

Positioning multiple high-speed electrical signal input terminals close together on one side of the modulator enables generation of DQPSK signals without the need to adjust for electrical signal lag on the drive circuit.

Furthermore, employing separate input terminals for the high-speed electrical signals mentioned above and the DC bias signals for controlling the modulator eliminates the need for an external electrical circuit to combine them.

Product samples of the new Fujitsu LN optical modulator will be on exhibit at the Optical Fiber Communication Conference and Exposition (OFC) and the National Fiber Optic Engineers Conference (NFOEC) 2007 in Anaheim, California, from March 27 - 29, 2007.

Sales Target

One billion yen in FY 2007 (year ending March 31, 2008).

For more information:

  • [1] Differential Quadrature Phase Shift Keying (DQPSK)

    A method for modulating digital signals in which 2 bits of data are allocated to each of 4 modulated optical phases (0°, 90°, 180° and 270°).

  • [2] LN optical Modulator

    A device that converts an electrical data signal into an optical data stream via the electro-optic effect of a LiNbO 3 crystal. There are intensity modulators for converting input electrical signals to optical intensity signals and phase modulators for converting them to optical phase signals. One of the LN modulator's features is modulation with minimal wavelength chirping. This is a desirable characteristic for ultra high-speed, long haul, and DWDM (Dense Wavelength Division Multiplexing) transmission.

About 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 for further information.

Press Contacts

Public and Investor Relations

Company:Fujitsu Limited

Customer Contacts

Optical Components Unit
Sales Department

E-mail: E-mail:
Company:Fujitsu Limited

All 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.

Date: 27 March, 2007
City: Tokyo
Company: Fujitsu Limited, , , , ,