New optical-fiber-cable installations in metro areas are focused on getting fiber closer to the customer to support a higher volume of high-speed revenue-generating services. Minimizing construction costs in metro areas is difficult since most urban duct networks are already populated with cable. Fortunately, two new types of fiber-optic cable are facilitating less expensive, incremental additions of fiber into metro networks without wasting precious space: microcables and blown fiber units.
Microcables have constructions similar to standard cables but are 40–50% smaller in diameter to facilitate their use in ducts less than a half-inch in diameter. A full range of options with up to 72 fibers has been introduced by a variety of cable suppliers during the last year.
Blown fiber units have been developed to support applications in which fiber is added in increments of less than 12. These products have diameters less than 3 mm and fit in 0.3-inch-diameter or smaller ducts. British Telecommunications has been using blown fiber units for over a decade, and other users have emerged in the last year (see "Better access: Where no fiber has gone before," Lightwave, July 2003, page 29).
Since microcables, blown fiber units, and microducts are designed primarily or exclusively for air blown or jetted installation techniques, minimal space can be allocated for tensile elements. Air blown techniques are the most benign method for installing optical-fiber cables. Further, using air to guide and "lubricate" the cable or duct installation allows the product to be installed in very small rights of way or in already-populated ducts.
To support these purpose-built cables, Working Group 3 for fiber-optic cable in IEC SC86A has spent the last two years working on a new product standard. A preliminary version went out for comment in the summer and was to have been reviewed at the next International Electrotechnical Commission meeting in Montreal last month.
Dr. Lisa A. Dixon, a product manager at OFS, represents the company in IEC SC86A WG 3 and ASTM's Committee F36 on Technology and Underground Utilities. She can be reached at 770-798-3787 or LAD13@ofsoptics.com.