Japan group claims optical transport breakthrough

Japan’s National Institute of Information and Communications Technology and Oki Electric Industry claimed a first on Wednesday with the carriage of data using a next-generation optical transmission technology on a metropolitan-area fiber-optic network.

In the demonstration, two channels of 10G bit/sec bandwidth were transmitted over a distance of about 100 kilometers, from central Tokyo to the NICT in the city of Tsukuba, and then back again using a system called Optical Code-Division Multiplexing (OCDM).

OCDM is a method for sending more than one signal down an optical fiber. Technologies such as dense wavelength division multiplexing already exist to squeeze more bandwidth out of an optical fiber, but researchers involved in the demonstration said OCDM can accomplish the task more economically and flexibly.

The total distance of the demonstration was 200 kilometers (124 miles) and is a record for OCDM, said Takeshi Kamijoh, general manager of Oki Electric’s advanced devices laboratory. Successful use of OCDM over such a distance means the technology is suitable for metropolitan-area networks, the citywide fiber-optic networks that are becoming common in many cities, he said.

The test was carried out on Japan Gigabit Network II (JGN II ), which is a testbed network linking 63 access points at research establishments and universities across Japan. Next Monday, a link to the U.S. from JGN II will be officially opened.