Fusion splicing
Encyclopedia
Fusion splicing is the act of joining two optical fiber
s end-to-end using heat. The goal is to fuse the two fibers together in such a way that light passing through the fibers is not scattered
or reflected
back by the splice, and so that the splice and the region surrounding it are almost as strong as the virgin fiber itself. The source of heat is usually an electric arc
, but can also be a laser, or a gas flame, or a tungsten filament through which current
is passed.
The process of fusion splicing involves using localized heat to melt or fuse the ends of two optical fibers together. The splicing process begins by preparing each fiber end for fusion. Fusion splicing requires that all protective coatings be removed from the ends of each fiber, a process called stripping
. The fiber is then cleaved
using the score-and-break method so that its endface is perfectly flat and perpendicular to the axis of the fiber. The quality of each fiber end is inspected using a microscope. In fusion splicing, splice loss is a direct function of the angles and quality of the two fiber-end faces. The two endfaces of the fibers are aligned, then are fused together. The bare fiber area is protected either by recoating
or with a splice protector. It is often desirable to perform a proof-test to ensure that the splice is strong enough to survive handling, packaging and extended use.
The basic fusion splicing apparatus consists of two fixtures on which the fibers are mounted and two electrodes. Inspection microscope assists in the placement of the prepared fiber ends into a fusion-splicing apparatus. The fibers are placed into the apparatus, aligned, and then fused together. Initially, fusion splicing used nichrome wire as the heating element to melt or fuse fibers together. New fusion-splicing techniques have replaced the nichrome wire with carbon dioxide (CO2) lasers, electric arcs, or gas flames to heat the fiber ends, causing them to fuse together. The small size of the fusion splice and the development of automated fusion-splicing machines have made electric arc fusion (arc fusion) one of the most popular splicing techniques in commercial applications.
Alternatives to fusion splicing include using optical fiber connector
s or mechanical splice
s both of which have higher insertion loss
es, lower reliability and lower return loss
es than fusion splicing.
Optical fiber
An optical fiber is a flexible, transparent fiber made of a pure glass not much wider than a human hair. It functions as a waveguide, or "light pipe", to transmit light between the two ends of the fiber. The field of applied science and engineering concerned with the design and application of...
s end-to-end using heat. The goal is to fuse the two fibers together in such a way that light passing through the fibers is not scattered
Scattering
Scattering is a general physical process where some forms of radiation, such as light, sound, or moving particles, are forced to deviate from a straight trajectory by one or more localized non-uniformities in the medium through which they pass. In conventional use, this also includes deviation of...
or reflected
Reflection (physics)
Reflection is the change in direction of a wavefront at an interface between two differentmedia so that the wavefront returns into the medium from which it originated. Common examples include the reflection of light, sound and water waves...
back by the splice, and so that the splice and the region surrounding it are almost as strong as the virgin fiber itself. The source of heat is usually an electric arc
Electric arc
An electric arc is an electrical breakdown of a gas which produces an ongoing plasma discharge, resulting from a current flowing through normally nonconductive media such as air. A synonym is arc discharge. An arc discharge is characterized by a lower voltage than a glow discharge, and relies on...
, but can also be a laser, or a gas flame, or a tungsten filament through which current
Electric current
Electric current is a flow of electric charge through a medium.This charge is typically carried by moving electrons in a conductor such as wire...
is passed.
The process of fusion splicing involves using localized heat to melt or fuse the ends of two optical fibers together. The splicing process begins by preparing each fiber end for fusion. Fusion splicing requires that all protective coatings be removed from the ends of each fiber, a process called stripping
Stripping (fiber)
Stripping is the act of removing the protective polymer coating around optical fiber in preparation for fusion splicing. The splicing process begins by preparing both fiber ends for fusion, which requires that all protective coating is removed or stripped from the ends of each fiber...
. The fiber is then cleaved
Cleave (fiber)
A cleave in an optical fiber is a deliberate, controlled break, intended to create a perfectly flat endface, perpendicular to the longitudinal axis of the fiber...
using the score-and-break method so that its endface is perfectly flat and perpendicular to the axis of the fiber. The quality of each fiber end is inspected using a microscope. In fusion splicing, splice loss is a direct function of the angles and quality of the two fiber-end faces. The two endfaces of the fibers are aligned, then are fused together. The bare fiber area is protected either by recoating
Recoating
Recoating is the process of restoring the primary coating to stripped optical fiber sections after fusion splicing. In the recoating process, the spliced fiber is restored to its original shape and strength, using a recoater. The stripped fiber section is recoated by filling a recoating resin,...
or with a splice protector. It is often desirable to perform a proof-test to ensure that the splice is strong enough to survive handling, packaging and extended use.
The basic fusion splicing apparatus consists of two fixtures on which the fibers are mounted and two electrodes. Inspection microscope assists in the placement of the prepared fiber ends into a fusion-splicing apparatus. The fibers are placed into the apparatus, aligned, and then fused together. Initially, fusion splicing used nichrome wire as the heating element to melt or fuse fibers together. New fusion-splicing techniques have replaced the nichrome wire with carbon dioxide (CO2) lasers, electric arcs, or gas flames to heat the fiber ends, causing them to fuse together. The small size of the fusion splice and the development of automated fusion-splicing machines have made electric arc fusion (arc fusion) one of the most popular splicing techniques in commercial applications.
Alternatives to fusion splicing include using optical fiber connector
Optical fiber connector
An optical fiber connector terminates the end of an optical fiber, and enables quicker connection and disconnection than splicing. The connectors mechanically couple and align the cores of fibers so that light can pass...
s or mechanical splice
Mechanical splice
A mechanical splice is a junction of two or more optical fibers that are aligned and held in place by a self-contained assembly...
s both of which have higher insertion loss
Insertion loss
In telecommunications, insertion loss is the loss of signal power resulting from the insertion of a device in a transmission line or optical fiber and is usually expressed in decibels ....
es, lower reliability and lower return loss
Return loss
In telecommunications, return loss or reflection loss is the loss of signal power resulting from the reflection caused at a discontinuity in a transmission line or optical fiber. This discontinuity can be a mismatch with the terminating load or with a device inserted in the line...
es than fusion splicing.
See also
- Termination and splicing.
- RecoatingRecoatingRecoating is the process of restoring the primary coating to stripped optical fiber sections after fusion splicing. In the recoating process, the spliced fiber is restored to its original shape and strength, using a recoater. The stripped fiber section is recoated by filling a recoating resin,...
- Stripping (fiber)Stripping (fiber)Stripping is the act of removing the protective polymer coating around optical fiber in preparation for fusion splicing. The splicing process begins by preparing both fiber ends for fusion, which requires that all protective coating is removed or stripped from the ends of each fiber...
- Optical communicationOptical communicationOptical communication is any form of telecommunication that uses light as the transmission medium.An optical communication system consists of a transmitter, which encodes a message into an optical signal, a channel, which carries the signal to its destination, and a receiver, which reproduces the...
- Optical fiberOptical fiberAn optical fiber is a flexible, transparent fiber made of a pure glass not much wider than a human hair. It functions as a waveguide, or "light pipe", to transmit light between the two ends of the fiber. The field of applied science and engineering concerned with the design and application of...
- Cleave (fiber)Cleave (fiber)A cleave in an optical fiber is a deliberate, controlled break, intended to create a perfectly flat endface, perpendicular to the longitudinal axis of the fiber...
- Fiber optic communications