This study was a joint effort between Verizon Technology and Corning Cable Systems. It was performed to investigate the possibility of catastrophic failures on SC/APC fiber optic connectors, with clean end faces, that are connected and disconnected under optical powers in the range 15 to 22 dBm (32 to 160 mW). Verizon is using optical power in this range at 1550nm, to carry analog video signal through feeder cables and connection elements in a passive optical network (PON), for Fiber-to-the-Premises (FTTP) applications.Testing was done under laboratory conditions at Corning Labs in Keller TX. Seven SC/APC connection samples (including two connectors and one adaptor per sample) were tested. The connector end faces were initially cleaned and inspected. For each of the six connection samples, the connectors were re-cleaned and inspected after completion of 12 connections at each power level. For one sample, the connectors were re-cleaned and inspected after completion of 100 connections at each power level, in order to determine the ultimate connection durability under high power. In this case, a total of 800 connections were performed under high power. In two instances, the insertion loss increased significantly without resulting to any permanent damage on the connector end faces. This was attributed to the inability of the contaminants to generate thermal damage to the connector end faces. Other mechanisms, such as scattering, may have also contributed to the high insertion loss. All the results indicate that no optical damage occurs if the end faces of the SC/APC connectors remain clean, for optical powers up to 22 dBm (160 mW).Actual environmental conditions in the field will differ significantly. Contamination particles on the end faces of the connectors may cause failure. In addition, during the cleaning process, particles swept by the ribbon of a cleaning tool or dragged against a dry or wet cleaning surface may pass temporarily across the fiber core area. These particles could cause connector end face damage, due to mechanical abrasion, or thermal damage from absorption of Infra-Red (IR) power. The optical power threshold for permanent (thermal) damage of connector end faces, contaminated with carbon black, has been reported to be approximately 16 dBm (40 mW).It is therefore recommended for high optical power connections that prior to mating, the connector end faces need to be inspected. If they are contaminated they must be cleaned at a power level not exceeding 15 dBm, to avoid connector damage during cleaning. The cleaned connectors must be re-inspected and coupled if the end faces meet the cleaning requirements. Subsequently, the optical power can be increased above 15 dBm to the proper operating level. If a connection shows high loss, the power needs to be reduced below 15 dBm and the connectors have to be uncoupled, cleaned, inspected in a safe manner and replaced if damaged.
© 2006 Optical Society of AmericaPDF Article