March 17, 2005 Tokyo, Japan -- Nippon Telegraph and Telephone (NTT) has successfully demonstrated 1,000 wavelength channel WDM transmission across an installed optical fiber. According to the carrier, using the 126-km JGN 2 test bed between Kyoto and Osaka, the experiment transmitted 10x more WDM channels with 8x the density, or 1/8 the wavelength spacing, of commercial systems.

According to the carrier, in conventional commercial systems, WDM is limited to about 100 channels, with each channel requiring its own semiconductor laser diode, making wavelengths difficult to control. For the demonstrated 1,000-channel WDM transmission, the carrier employed its multi-wavelength generation and multiplexer/de-multiplexer technologies.

In the experiment, a multi-wavelength lightwave source, or Supercontinuum (SC), generated more than 1,000 high-quality wavelengths with fixed frequency, or wavelength, spacing. SC is a phenomenon whereby the optical spectrum explosively expands when an intense light source such as an optical pulse traverses an optical material, generating new wavelengths in a chain reaction.

In the demonstration, the SC source successfully generated 1,000 individual wavelengths with 6.25-GHz spacing, which the carrier says is 8x the density of commercial systems. According to the carrier, its multiplexer/de-multiplexer's newly developed 6.25 GHz-spaced arrayed waveguide grating (AWG) filters separated the individual wavelengths with minimal crosstalk.

Established in April 2004 by Japan's National Institute of Information and Communications Technology (NICT), the JGN 2 test bed is an ultra-fast, open network environment designed to enable collaboration among industry, academia, and the government in the research and development of IP and optical wavelength networks.

The experiment was partly supported by a grant from NICT. Through the experiment, the carrier aims to develop photonic networks combining advanced WDM and wavelength routing technologies, in order to construct high-quality, flexible backbones with high numbers of useable WDM channels.