Figure 6-5.A glass or ceramic alignment tube for mechanical splicing.
diameter of the alignment tube. If the inner diameter is
too large, splice loss will increase because of fiber
misalignment. If the inner diameter is too small, it is
impossible to insert the fiber into the tube.
Mechanical splices also may use either a grooved
substrate or positioning rods to form suitable
V-grooves for mechanical splicing. The basic
V-grooved device relies on an open-grooved substrate
to perform fiber alignment. When you are inserting the
fibers into the grooved substrate, the V-groove aligns
the cladding surface of each fiber end. A transparent
adhesive makes the splice permanent by securing the
fiber ends to the grooved substrate. Figure 6-6
illustrates this type of open V-grooved splice.
V-grooved splices may involve sandwiching
the butted ends of two prepared fibers between a
V-grooved substrate and a flat, glass plate.
Additional V-grooved devices use two or three
positioning rods to form a suitable V-groove for
splicing. The V-grooved device that uses two pois-
tioning rods is the spring V-grooved splice. This
splice uses a groove formed by two rods positioned
in a bracket to align the fiber ends. The diameter of
the positioning rods permits the outer surface of
each fiber end to extend above the groove formed
by the rods. A flat spring presses the fiber ends into
the groove maintaining fiber alignment. Trans-
parent adhesive completes the assembly process
by bonding the fiber ends and providing index
matching. Figure 6-7 is an illustration of the
spring V-grooved splice. A variation of this splice
Figure 6-6.Open V-grooved splice.