IEC discusses effect of deployment on PMD

Dec. 1, 2004

Polarization-mode dispersion (PMD) is a statistical phenomenon whose value can change with time, temperature, wavelength, and deployment conditions. For that reason, standards bodies have chosen to specify PMD in a statistical manner by using the parameter PMDQ. This parameter represents a statistical extreme of the distribution of PMD values that result from a concatenation of several randomly selected fibers.

Although the International Telecommunication Union and International Electrotechnical Commission specify PMDQ only on cabled fiber (fiber that has been packaged into a cable), IEC 60793-1-48 provides guidance on how to deploy uncabled fibers when measuring them. Section 5.2.1 of that document describes two deployment conditions: a large-diameter spool configuration and flat-surface condition. In both cases, the fiber must be under low tension, not cross over itself, and have bending radii larger than 15 cm.

At last May’s meeting of IEC SC86A/WG1, chaired by Allen Cherin of OFS, presentations were made by Arthur Barlow of PerkinElmer and yours truly on the effects of fiber deployment. These presentations clearly reinforce the basis for the IEC 60793-1-48 deployment conditions. Fibers wound under other conditions such as with several layers on a shipping spool can produce grossly misleading results. For poorly manufactured fiber, deployment on a shipping spool can mask the fiber’s true, or intrinsic, PMD. For good-quality fiber, the PMD can be artificially elevated.

While that should not be surprising, different results can also be obtained between the two recommended IEC deployment conditions. Poorly manufactured fibers tend to have higher PMD when measured on a flat surface than on a large-diameter spool. Good-quality fibers tend to be less sensitive to deployment and measure about the same PMD in either configuration. These differences will need to be addressed if a reference deployment condition is needed to compare fiber quality.

James J. Refiis a fiber optics consultant and secretary of IEC SC86A/WG1. He can be reached at [email protected].

Sponsored Recommendations

ON TOPIC: Innovation in Optical Components

July 2, 2024
Lightwave’s latest on-topic eBook, sponsored by Anritsu, will address innovation in optical components. The eBook looks at various topics, including PCIe (Peripheral...

Connecting the world, one fiber at a time

Dec. 12, 2023
The world runs on ethernet: the future of higher speeds

New Optical Wavelength Service Trends

July 1, 2024
Discover how optical wavelength services are reshaping the telecom landscape, driven by rapid expansion and adoption of high-speed connections exceeding 100 Gbps, championed by...

Data Center Network Advances

April 2, 2024
Lightwave’s latest on-topic eBook, which AFL and Henkel sponsor, will address advances in data center technology. The eBook looks at various topics, ranging...