Quality of Fibre Optic Terminations

As data rates, loads, number of wavelengths, distance and optical power all increase, the need for high quality, reliable connector terminations has never been greater. So often, it is the handful of pounds or dollars saved by compromising cable assembly quality that will bring down a whole network, costing tens of thousands in lost revenue every time. To ensure a good quality connector termination, 100% inspection of the following parameters is essential:

  1. Insertion Loss
  2. Return Loss
  3. Endface Geometry
  4. Endface Defects

There are other factors, which can greatly influence the quality and reliability of a connector termination.

Two examples are:

1. Epoxy.

During mating, there is an axial load placed on the fibres at the connection point. The epoxy used needs to have a high enough glass transition temperature (Tg) in order to prevent fibre pistoning (where the fibre is pushed back slightly). It is also very important that the epoxy be degassed. This is done by placing the epoxy in a vacuum chamber to remove any air introduced into the epoxy during mixing. If there are air bubbles in the epoxy there will be reduced support for the fibre.

2. Cable Retention.

Most fibre optic connectors rely on the kevlar being crimped onto the back of the connector for strain relief. It is important that this process be controlled in order to guarantee the level of cable retention required. There are variables, which need to be examined before this process is carried out, e.g. quantity of kevlar in a particular batch of cable and crimp tool wear. In order to control this, pull tests should be performed regularly, and always when a new batch of cable is being used. Fibrepulse performs pull tests on all connector-cable-crimp tool combinations at the start of, and at regular intervals during every assembly batch, with the result recorded.