Laser Focus World

CWDM breathes life into metro, access, and enterprise applications: simpler optics, uncooled lasers, and zero-water-peak fibers have paved the way for one of the few bright spots in telecom these days. Combining CWDM with DWDM may be the ultimate solution. (Optoelectronic applications: telecommunications).

Long considered the less sophisticated cousin to dense wavelength-division multiplexing (DWDM), coarse wavelength-division multiplexing (CWDM) is emerging as one of the few revenue opportunities in telecommunications and data communications these days. With cost considerations now at the forefront of carrier investment in optical networks, the CWDM infrastructure offers several advantages over DWDM--even beyond the standard 50-to 80-km distances usually associated with CWDM.

The very characteristics that make DWDM attractive for long-haul applications--primarily the ability to significantly increase the bandwidth of a single fiber and offer hundreds of transmission channels in the process--also make it much more complex and expensive than CWDM. With carrier attention turning away from the saturated long-haul market, CWDM has gained new respect as carriers seek simpler and more cost-effective network solutions for the metro, access, cable TV (CATV), and enterprise markets (for more on CATV see p. 65). In addition to seeing increasing sales, CWDM component suppliers say that CWDM is becoming a universal standard, with growing adoption in Europe, Asia, and North America.

Filling a gap

Coarse WDM technologies have actually been in use since the early 1980s, primarily in 850-nm multimode local area network (LAN) applications. (1) But in the late 1990s, spurred by increasing bandwidth demands and a growing need to ease data traffic bottlenecks in metro, access, and enterprise networks, carriers began turning to CWDM as a lower-cost alternative to DWDM for a broad range of multipurpose, multimode applications, including local-, wide-, and storage-area networks. …

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