Fujitsu and University of Tokyo achieve 25G via quantum dot laser

MAY 20, 2010 -- Fujitsu Ltd., Fujitsu Laboratories Ltd., and the University of Tokyo have announced what they tout as the world's first quantum dot laser based 25-Gbps high-speed data transmission.

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MAY 20, 2010 -- Fujitsu Ltd., Fujitsu Laboratories Ltd., and the University of Tokyo have announced what they tout as the world's first quantum dot laser based 25-Gbps high-speed data transmission.

Researchers are investigating quantum dot lasers as a next-generation semiconductor light source for high-speed data transmissions that consume minimal power. Quantum dot lasers are semiconductor lasers that employ quantum dots -- nanometer-sized semiconductor particles -- as an active material for lasing. Quantum dot lasers feature significant advantages over other types of semiconductor lasers, the researchers say, such as being less sensitive to temperature fluctuations and offering lower power consumption, greater transmission distances, and faster speeds.

As increasing the number of quantum dots improves operation speed, layers of quantum dots with a higher density than conventionally employed were stacked, thereby doubling the laser's operation speed and enabling a significant improvement over previous technologies (see below). As part of this, the research team developed technology for forming high-density indium-arsenide (InAs) quantum dots on the surface of a gallium-arsenide (GaAs) substrate. This doubles the number of quantum dots per unit area to 6x1010 per square centimeter.

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Figure 1: Quantum dot laser featuring an active layer containing high-density arrays of quantum dots



This new technology is expected to be employed next-generation high-speed data communications at 100 Gbps.

Details of the technology will be presented at the Conference on Lasers and Electro-Optics and the Quantum Electronics and Laser Science Conference (CLEO/QELC 2010), being held from May 16-21 in San Jose, U.S.

Part of this research belongs to a project contracted to the Photonics Electronics Technology Research Association (PETRA) by the New Energy and Industrial Technology Development Organization (NEDO), while part of the research was carried out under Japan's Ministry of Education, Culture, Sports, Science and Technology's Special Coordination Funds for Promoting Science and Technology.

In addition, joint research and development of quantum dot lasers is being pursued through collaboration between Professor Yasuhiko Arakawa's laboratory at the University of Tokyo, Fujitsu, Fujitsu Laboratories, and QD Laser, Inc.

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