Fiber Optic Termination Method
There are plenty of fiber connector termination method, each with its own advantages and disadvantages, Generally, in most case, both SM and MM cable are pulled without termination, operators strip the fiber cable by special toolkit and splice the fiber cable with pigtails, and protect the splice by heat shrinkable sleeves, and manage them inside closures, terminal box, cross cabinet, or ODF in the central office. the splice will have less loss compared with active connection.
even through terminate fiber cable after pulling is popular, however, pre-terminated cables are being installed with connectors also very common like in CATV network implementation. but you will know there will be several potential challenges like the fiber cable lengths must be very precise, otherwise, too long or too short will result problems, if cable too long, you need extra space for store the cable, while if it is too short, it is very annoy that you need re-install cable or cut connector, splice with new cable, beside it. connector protection is another key factor that operators need to take care, not brake it or contaminate the fiber cabnector. generally in the data center, it will pull cable with pre-terminated MPO/MTP connector in one end, and with 4/8/12 LC/SC connector in another end.
Direct Termination – Hot melting, expoxy, anaerobic adhesive, crimping and polishing
Most fiber connectors are the simple “epoxy/polish” type where the fiber is glued and insert into the connector with epoxy and the end polished with different polishing film. The epoxy/polish type provides the most reliable connection with lowest losses (less than 0.5 dB) and the lowest costs, especially if you are doing a lot of fiber connectors. The epoxy can be allowed to set overnight or heat in an economic heat oven. Do not use a “heat gun” to cure the connector, because it is very hard to control the heat to the epxoy
The hot melting is firstly introduced to the market by 3M, the connector that already has the epoxy (heat set glue) inside. You strip the cable, insert the fiber core into different connector based on active device fiber interface, crimp it, and put it in a special heat oven. In a few mins, you remove the connector after the glue melted, let it cool and it is ready to polish. Fast and easy, low loss, but not as economic as the epoxy type, it is seen as suitable for relatively small quantities of fiber connectors.
These fiber connectors use a quick setting adhesive to replace the epoxy. The worked very well if you can control the temperature and time very well, because generally its quite difficult to curl it hormoney, so only use them indoors. Most connectors use epoxy (AD353) or other chemical adhesives (generally hard to import from overseas for small quantity) to hold the fiber in the connector. Use only the specified epoxy, as the fiber to ferrule bond is critical for low loss and long term reliability
instead of add glue to the fiber in the fiber connector, It is very easy to use a crimp on the fiber to hold it tightly. This method with fast termination speed, and of course, higher losses. the fiber connectors are cost higher than epoxy polishing types. A good choice only if you install small quantities and the customer will accept them.
Hints for field terminating connectors
l Have the right fiber tools for the cable termination and ensure they are in good condition.
l Is your Test Equipment and Leads in perfect condition? need calibration or not
l Ensure you have the ways to inspect the end-faces.
l Dirt, dust, small particles are your enemies during fiber optic network installation.
l Use lint-free wipes to clean every connector before connecting or testing it.
l Don’t work under heating vents, they distribute dirty air.
l Don’t over-polish, too much polishing is just as bad as too little. Polish too much and you create a concave fibre surface, increasing the loss.
l Change polishing film regularly. Polishing builds up residue and dirt on the film that can cause problems.
l Put covers on connectors and patch panels when not in use.
l Inspect and test, then document.
Splicing – Mechanical or Fusion
There are two types of splices, fusion and mechanical, and the choice is based on quantity, expected lifecycle and location.
These are made by “welding” the two fibres together usually by an electric arc. Obviously, it is not advisable in an explosive atmosphere. A good fusion splicer is usually fully automatic which gives maximum assistance and ensures good splices time after time. This is the preferred option for field termination of Fiber Systems due to the accuracy and consistency of Fusion Splicing of warranted pre-terminated pigtails.
For full details on the correct procedures for Fusion Splicing please visit the following link.
These are alignment devices that hold the ends of two fibres together with some index matching gel or glue between them there are a number of types of mechanical splices however they should only be used for temporary repairs and not long term installations covered by the 25 year warranty.
The pre-terminated fibre optic portfolio is available in OM1, OM2, OM3 and OM4 multimode and OS1 and OS2 single-mode categories of system. The choice of cable type allows for the assembly to match the environment that it will be installed. Standard fiber termination is a costly exercise requiring highly skilled engineers and specialist equipment to complete an installation. With the fiber pre-terminated solution it provides a fully tested fiber loom that can be installed by non-specialist personnel, vastly reducing the installation time onsite.
Using pre-terminated assemblies is no excuse for a lack of cleanliness within the Communication Room the fiber connectors are still susceptible to air borne contamination, the rules regarding inspection and cleaning prior to plugging a connector into a device or patch panel outlined earlier remains the same.