It’s an easy task to overlook. Most people purchase optical transceivers, deploy them in their networks, and don’t think about them again until the data transmission over the link slows down or stops completely. When this happens, it seems fairly intuitive to blame the device that transmits and receives the data: the optical transceiver. In many cases, the offending transceiver is sent back to the manufacturer as defective. However, evidence suggests that less than 25% of optics returned are actually failed; their lasers are entirely functional.
The most common cause of these of these failures is entirely preventable: the optics just need to be thoroughly cleaned. Unclean optics and fiber cable connectors can increase bit error rate, which in turn slows down transmission speeds. A fully blocked optic will result in a complete loss of signal.
Photo A shows a clean optical transceiver, as viewed through a scope. The light center of the circle is the fiber core, which must remain clear for optimal data transmission. In Photo B, the fiber core is completely obscured by a contaminant. It doesn’t take much to fully block the connection. For example, a 1-micrometer dust particle can cause 0.05 dB of signal loss, and a 9-micrometer speck can block the fiber core entirely. That’s 1/5 of the width of a human hair!
To avoid all these types of contamination, stay tuned as we continue this series with a step-by-step guide on proper cleaning and handling methods for optical fiber and transceivers.