UNDERSTANDING FIBER OPTICS
CONNECTORS TYPES
Fiber termination in the ferrule Whatever the needed connector, the first step consists in inserting the fiber in a ferrule, to allow to simplify the fiber handling with less risk to damage it. This ferrule is generally made of ceramics and is manufactured with high precision machining process.
ceramic ferrule
fiber optic cable
glue
bare fiber (125 µm )
The different steps to terminate the fiber in the ferrule are: • fiber stripping to keep only the active layers (core and cladding). • fiber epoxy bonding in the ceramic ferrule. The fiber is introduced into the ceramic ferrule hole whose diameter is very precise, and adjusted to that of fiber. • fiber cleaving at the ceramic ferrule surface. • polishing of the end of the ceramic ferrule. Using lapping films of increasingly fine grains, the fiber surface is perfectly well polished, and all the awkward residual particles have been eliminated.
Butt joint technology Principle:
ceramic ferrule
The principle of the butt joint connectors consists in putting in physical contact the two ceramic ferrules. To realign perfectly fibers face to face, we use an alignment sleeve generally in ceramics. The light passes thus directly from one fiber to the other.
fiber
sleeve
Defects: The alignment of fibers is never perfect, some light is lost when going from one side to the other. This loss can be high according to the residual defects of alignment or polishing:
transverse shift
air gap (bad contact)
angular shift
bad polishing
p5
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