Repeaterless DWDM – A 317km Caribbean Festoon Segment Upgrade By Eyal Lichtman and Michael Schneider
Introduction Put into service in June 1997 the Antillas-1 cable system serves the Caribbean basin and spans to link the Dominican Republic and Puerto Rico. Originally, it was designed to transmit voice, data and images at the rate of 622 million bits per second on each of its six fiber pairs. The system has been since upgraded to carry traffic at the STM-16 rate of 2.5 Gb/s per pair. Recently, Antillas-1 has been tested to determine how dense wave division multiplexing (DWDM) can be used to further expand the capacity of the cable system. This new capacity will be used to serve a portion of the proposed Trans-Caribbean Cable Network (“TCCN”). The project was conceived to service the ever-growing Internet, data and voice traffic demands of the Caribbean. The TCCN will offer high-speed undersea fiber-optic cable connectivity from many locations in the Caribbean to Miami, Florida through a combination of segment construction and existing segment upgrades. Trans-Caribbean Cable Company (“TCCC”) is the management organization for planning, building, operating, and maintaining the Trans-Caribbean Cable Network. TCCC envisions that TCCN will become the Caribbean region’s common, carrier-
neutral platform that will provide the capacity needed to stimulate the growth of the Internet and other telecom services in the region.
The Undersea Link
The 317km undersea link was composed of two types of fibers: Dispersion-shifted fiber (G.653 DSF) over the first 30km of the link, and special undersea fiber (G.654, also known as Z fiber) This paper describes a field trial held by ECI over the rest of the link. In addition, a short piece Telecom and IPG Photonics in the Caribbean of erbium-doped fiber (EDFA) was placed 67km where eight DWDM channels at 2.7Gb/s each before the fiber end to provide a remote optical were successfully transmitted over a repeaterless amplification (ROPA). The undersea link is link,link i.e.ofinserting the DWDM channels ROPA side, as presented by Fig.1b undersea 317km. This is the longest spanfrom the presented by Fig.1a below. below. The link “rotation” enables the DWDM transmission since in that configuration of Antillas-1 between the cities of Punta Cana the G.653 fiber is located at the end of the span. The signal power there is too low to (DR) and Isla Verda (PR). cause any nonlinear degradation.
1a 30km G.653
220km G.654
Erbium
67km G.654
1b 67km G.654
Erbium
220km G.654
30km G.653
Fig.1: The original undersea link (a) and the “rotated” undersea link (b). (The upper arrow shows the signal propagation direction.
Raman Amplification The 317km undersea link results in a loss of about 60dB that could not be passed with standard erbium-doped fiber amplifiers (EDFAs). To overcome such a high loss, ECI
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