Advantages and disadvantages
There are several advantages. They do not require any power supplies. Indeed, many designs require no tools at all beyond a stripper and cleaver, so the mechanical splice can be used in situations that may be considered hostile to many fusion splicers. Mechanical splices are often re-usable and can be fitted in less than a couple of minutes, which makes them ideal for temporary connections. The disadvantage is that they cause a loss, called the insertion loss, of about 0.1–0.3 dB per connection which is significantly higher than a good fusion splice. This would suggest the use of a fusion splice as the first choice in situations where losses are critical. Mechanical splices can be used to connect either singlemode or multimode fibers.
How they work
In essence, it is very easy. The fiber must be stripped, cleaned and cleaved. They must then be aligned and then held in position either by epoxy resin or by mechanical clips. There are only three basic designs.
The prepared fibers are placed in the groove and their ends are brought into contact. Some index matching gel is used to bridge the gap between the two ends to prevent gap loss and to reduce Fresnel reflection. A gripping mechanism then holds the fibers in position and provides mechanical protection for the fiber. As an alternative to the index matching gel, an index matching epoxy can be used. This performs the same index matching task as the gel but also holds the fiber in position. It is usually cured by UV light.
- Strip, clean and cleave the fiber leaving about 12 mm of primary buffer removed.
- If re-using the splice (if this is possible) clean with isopropyl alcohol and a piece of lint free cloth and use a syringe to inject a small bead of index matching gel into the center of the splice.
- Release the small clip at one end of the splice and insert the fiber until it comes to a stop. Operate the clip to lock the fiber in position.
- Release the clip at the other end and insert fiber until it comes up against the fiber already loaded. Operate the clip to lock that fiber also.
- Test the operation and if not satisfactory, the clips can be released to allow the fiber positions to be optimized.