Advice on purchasing fiber-optic connectors

As a fiber-optic component value-added distributor and a test equipment manufacturer, I feel compelled to respond to points made in "Sandia installation uncovers fiber issues" (June 1996, page 71). The article points out that simply selecting a quality connector does not ensure a quality end-product. Many people think that terminating optical fiber is a matter of stripping cable, gluing it into the ferrule and polishing. Testing a fiber-optic termination for three major performance criteria is equally important, however. These mandatory test parameters include insertion loss, return loss (or back reflectance) and end-face profilometry (protrusion/undercut, radius of curvature and apex, all of which are measured by an interferometer). For example, the Sandia team learned that profilometry was an essential quality test recommended by Bellcore GR-326, and should be--but is not always--practiced by cable-assembly operations and field installers.

End-users often standardize on a particular connector manufacturer`s part number while neglecting to qualify the cable-assembly house as a quality supplier. Although most connector and fiber manufacturers produce a high-quality raw component, the termination supplier--whether in-house or outside vendor--directly contributes at least 75% of the final product quality. As the Sandia team experienced, real-world performance does not always match the component manufacturer`s data sheet.

Although the material cost of a failed connector may be tens of dollars, the service expense to identify and correct the problem can run into thousands of dollars, including time, labor and travel--much more than the incremental cost of a quality product backed by a qualified supplier. Demanding ISO certification does not always guarantee performance quality; it only indicates compliance to a defined set of processes.

To ensure quality at Rifocs, we routinely test production samples with a profilometer and temperature cycle them to certify continued process compliance and performance.

My advice to customers is: Know your supplier, understand the technology, and visit the vendor to evaluate his ability to supply a quality product.

Dennis Horwitz, vice president

Rifocs Corp.

Camarillo, CA