More Confusing Stuff About Fiber Optics
In this month’s fiber optics column (see page 112) and July’s quiz, I discussed some of the most confusing topics in fiber optics, but there are more. Here’s additional questions about bending specs for cables and bend-insensitive fibers, which is a topic that confuses people in fiber optics.
1. Optical fiber cable has a minimum bend radius or diameter because ______.
Correct Answer: All of the above
2. Manufacturers are moving from specifying bend radius to bend diameter. The diameter is ______ the radius.
Correct Answer: Twice
3. If the specification for minimum bend radius under tension is 20 times the cable diameter, the minimum bend diameter would be ______ times the cable diameter.
Correct Answer: 40
4. Bend diameter is used because it more easily relates the cable diameter to the diameter of pulleys and capstans used in installing cables and the size of service loops used to store cable.
Correct Answer: True
5. To reduce the sensitivity of fiber to bending losses, bend-insensitive (BI) fiber was introduced more than a decade ago, but early BI fiber types ______.
Correct Answer: Caused excess loss when joined to regular (non-BI) fiber
6. When BI fibers were used as reference cables for testing, ______.
Correct Answer: All of the above
7. You can tell if single-mode BI and non-BI fibers are joined in a link because the OTDR trace will show high loss in one direction and a gainer in the other direction.
Correct Answer: True
8. The compatibility of early BI fiber designs caused testing standards for multimode fiber to ______.
Correct Answer: Ban BI fibers to be used as reference cables for all multimode testing
9. Manufacturers of fiber responded to the problems of BI fiber compatibility by ______.
Correct Answer: All of the above
10. The manufacturers of single-mode fibers are converting most of their fibers to BI fibers because ______.
Correct Answer: So much BI fiber is being used in microcables and high-fiber-count cables
Score: