EoW May 2013

Technical article

This, in turn, will expand the available system solutions to a broader section of customers, while providing optimal density, flexibility and performance of fibre in enterprise applications. n 7 Acknowledgments The author would like to acknowledge the help of Ken Nardone, Henry Rice, Bill Jacobsen and Aly Fahd in obtaining data and test information for this paper.

Traditional fibre cables allow the fibre to slide back in the jacket enough for connectors to be attached, sometimes as much as two millimetres. Thus, connectors were designed with backshells that can account for the lack of additional empty space in the cores. These connectors still conform to GRS 326 performance levels or higher. 5 Thermal balancing Finally, since the tape and jacket are bonded together around the glass, thermal performance balancing was required to enable the entire cable to perform under standard thermal conditions. Each material – glass, tape and jacket – has a different level of thermal coefficient of linear expansion. This means that each material within the cable will expand or contract at different rates under different temperature conditions. For example, plastics typically expand and contract up to two orders of magnitude more than glass. In designing this new fibre, Aramid yarn was known to have a negative coefficient of linear expansion. But bonding everything together, most of the effects of thermal coefficients of linear expansion were virtually neutralised. In the end, the cable behaves very similar to the actual glass in terms of expansion and contraction, performing from -40 degrees Celsius to 70 degrees Celsius with minimal attenuation changes. cables typically perform from 0 degrees Celsius to 50 degrees Celsius – as required by plenum cable standards. 6 Conclusions As optical fibre solutions evolve to areas where copper once ruled, the importance of having the same handling, installation and management characteristics as copper wire cannot be underestimated. Optical cables need to have enough strength to be pulled, twisted and cornered similar to copper without affecting performance. By designing new cables that eliminate air and space inside the cable, smaller footprints can be achieved. Replacing the loose Aramid yarns with tape wraps and bonding the cable elements together is enabling a new evolution in small form factor optical micro-cables. Conventional plenum rated

This paper was presented at the IWCS symposium November 2012.

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May 2013