Dutch Claim Lead in Fiber Tests
Charles T. Troy
EINDHOVEN, The Netherlands --Heroes are back. A standard feature of the fiber optic scene in the 1980s, so-called hero experiments, in which researchers vie for records in terms of bits times kilometers of transmission, faded away in the push for installing more and more miles of fiber. Today, with the emphasis on squeezing increasing amounts of data transmission from existing fiber via optical amplifiers and wavelength division multiplexing (WDM), the race has been rekindled. Back in February the Optical Fiber Communication Conference was awash with papers describing experiments where trillions of bits were sent over distances of up to 350 km -- mainly relying on WDM techniques.
Fujitsu Laboratories reported 1.1 Tb/s via 55-channel WDM over 150-km, 1.3-µm, zero-dispersion single-mode fiber. AT&T Research boasted 1 Tb/s using WDM and polarization multiplexing for a total of 50 channels. NTT described a system for 100 Gb/s over 10 channels using optical time division multiplexing. Finally, Corning and Siemens reported 80 Gb/s over 350 km using Corning's optical pumping and negative dispersion fiber at 1550 nm and eight channels.
The newest entry in the hero experiment sweepstakes is a team from Philips Optoelectronics Centre (POC) and the Telecommunication Technologies and Electromagnetism Group of the Eindhoven University of Technology. The Dutch team claims a world record for amplified optical transmission with a single-channel signal of 10 Gb/s for a distance of 420 km.
The Philips/Eindhoven team said the key was the use of optical semiconductor amplifiers, called polarization-insensitive quantum-well amplifiers, developed by POC. The record, obtained using 1310-nm single-mode fiber, is said to surpass the record of 2.5 Gb/s over 500 km held by Japanese researchers. That experiment reportedly used special fibers designed for undersea links. The Dutch experiment was done in a laboratory using standard fiber.
The researchers are part of a European collaborative project called UPGRADE, which is part of the ACTS (Advanced Communication Technologies and Services) program of the European Community. One of ACTS' goals is an eventual 10-Gb/s link between Lisbon and Madrid using the existing optical fiber infrastructure.
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