Field assembly connectors are quicker and easier to assemble and terminate, but many in the industry raise concern over their long-term reliability. Technical and scientific community should not fall prey to the stereotypes, but unfortunately, many of the industry experts are yet to be convinced on the power of field assembly connectors.
It is a fact that fusion connection is a physical union of two glass threads that provides lowest possible loss due to connection loss, typically in the range of less than 0.05dB. A quick check on the technical data sheets of industry leading suppliers of Field Assembly connectors reveals that the typical loss from mechanical connection falls around less than 0.1dB.
What is the impact of 0.05dB over an FTTH network of 20 kilometers? Let us have a look before we jump in to conclusion.
An FTTH network typically spans around 20 kilometers. Considering an optical loss of 0.25dB/km maximum for the fiber at 1550nm, the attenuation contributes 5 dB loss. Loss due to connectors at the equipment side and splices in between contributes around 2.5dB to make a subtotal of 7.5dB. Splitters are common in PON network and usually it is two-stage splitting such as 1×4 and 1×8. Loss due to 1×4 splitting is around 8 dB and that due to 1×8 splitting is around 11 dB. Subtotal loss due to splitters is 19dB. Thus we get a total loss of 26.5 dB irrespective of the type of last mile connection.
In case of Field Assembly connector, typical loss is 0.2 dB. If we use two Field assembly connectors at the last mile, the subtotal loss would be 0.4 dB and the Total network loss would be 26.9 dB
In case of splicing, the typical loss is 0.05 dB and thus the subtotal loss would be 0.1 dB. Thus we get a total network loss of 26.6 dB.
For networks using field Assembly connectors, average loss would be 1.345 dB/km and for networks using splicing method, the average loss would be 1.33 dB/km. Per kilometer loss is higher by 0.015 dB for Field Assembly connectors, which is very negligible considering the loss budget of 28 dB for FTTH networks.
The author does not have any business interest to promote field assembly connectors, but just presenting the factors that may help you to take right decisions. Most of the concerns on field assembly connectors arise from their long-term performance and reliability as they utilize the index-matching gel/gum. Globally leading manufacturers utilize high precision manufacturing technologies and high quality material to assure the long-term performance. Cheaper products will have their own risk. We should not compromise on quality to save 20 or 30 cents.
Conclusion: Field Assembly Connectors are recommended for FTTH Networks. You need to buy from good and reputed suppliers. Never ever compromise on quality. Compromising on quality has high risk on the service quality and also your own reputation as a reliable person in the industry.