SPLICING

SPLICING AND ITS APPLICATIONS

- S P L I C E S J O I N T O G E T H E R T H E E N D S O F

T W O O P T I C A L F I B E R S I N A

C O N N E C T I O N T H AT I S I N T E N D E D T O

S TAY C O N N E C T E D

CONNECTORS SPLICES

Nonpermanent Permanent

Simple to use once mounted

Lower attenuation

Factory installable on cables

Lower back-reflection

Allow easy reconfiguration

Easier to seal hermetically

Provide standard interfaces

Usually less expensive per splice

More compact

- SPLICES HAVE LOWER LOSS AND BETTER MECHANICAL INTEGRITY THAN CONNECTORS

- SPLICES JOIN LENGTHS OF CABLE OUTSIDE BUILDINGS, CONNECTORS TERMINATE CABLES INSIDE BUILDINGS

- LOWER ATTENUATION OF SPLICES IS IMPORTANT FOR INSTALLING SYSTEMS THAT SPAN TENS OF THOUSANDS OF KILOMETERS

- PHYSICAL CHARACTERISTICS OF SPLICES ARE IMPORTANT ESPECIALLY CONSIDERING THEY HAVE TO WITHSTAND THE HOSTILE OUTDOOR ENVIRONMENT

- TEMPORARY SPLICES MAY BE NEEDED IN EMERGENDY REPAIRS OF BROKEN CABLES AND TESTING DURING INSTALLATION OR RENOVATION OF A CABLE SYSTEM

SPLICING ISSUES AND PERFORMANCE

M A I N C O N C E R N S W H E N D E A L I N G

W I T H S P L I C I N G I N C LU D E M A N Y O F

T H E S A M E C O N C E R N S A S T H O S E

D E A L I N G W I T H C O N N E C T O R S , S U C H

A S … OPTICAL CHARACTERISTICS OF THE FINISHED SPLICEPHYSICAL DURABILITY

EASE OF SPLICING

• SPLICES BOND TWO FIBERS BY MELTING (FUSING), GLUING, OR MECHANICALLY HOLDING THEM IN A TIGHT STRUCTURE

• INTRINSIC LOSSES ARE LOSSES AS A RESULT OF DIFFERENCES BETWEEN FIBERS BEING SPLICED

• EXTRINSIC LOSSES ARE LOSSES AS A RESULT OF THE NATURE OF THE SPLICE ITSELF (MISALIGNMENT OF FIBER ENDS, QUALITY OF END PREPARATION, REFRACTIVE-INDEX MATCHING BETWEEN ENDS, CONTAMINATION, ETC.)

• TOTAL LOSS CAN BE VERY LOW, NEAR 0.05 dB, IN PROPERLY MADE SPLICES

• SIGNS OF DEFECTIVE SPLICE: HIGH BACK-REFLECTION OR ATTENUATION

• MECHANICAL AND FUSION SPLICES ARE PROTECTED BY COATINGS, CLADDINGS, AND OR JACKETS

QUESTION #1:WHAT IS THE DIFFERENCE

BETWEEN EXTRINSIC AND INTRINSIC LOSSES?

TYPES OF SPLICING

1. Fusion Splicers- melts the ends of two fibers together so they fuse. Something that can closely relate would be welding metal.

Usually expensive to create but requires almost no consumable costs. Utilizing fusion splicers generally results in better optical characteristics

2. Mechanical Splicers- Holds two fiber ends together without welding them, using a mechanical clamp and/or glue.

Less expensive to create but consumable costs per slice are much higher

Usually has a higher loss than fusion splicers

Steps for fusion splicing1. Protective plastic coating or jacket must be stripped from a

few millimeters to a few centimeters of fiber at the ends to be spliced.

2. The fiber ends must be cleaved to produce faces that are within 1 to 3 degrees of being perpendicular to the fiber axis.

3. Ends must be kept clean until they are fused

4. You can choose to align the fibers either manually or automatically. The higher the price of the equipment, the better the alignment.

5. Once aligned, these ends are then pushed together so that power transmission can be tested to show if they are properly aligned.

6. If results are satisfactory, the arc is fired to weld the two fibers together

7. After the joint cools, it can be recoated with a plastic material to protect against environmental degradation

8. Finally, the splice assembly is closed mechanically for protection, which in turn is mounted in a splice enclosure.

MECHANICAL SPLICING TERMS AND TYPES• Back Reflection- the % of power reflected back from a

particular point in a light path.

• These reflections can be reduced by using epoxy (thermosetting polymer) or by inserting a fluid or gel with a refractive index close to glass into the splice

Capillary Splice• Inserting two fiber ends into a thin capillary tube.

• The cladding of the fiber is inserted into a tube with an inner diameter that matches the outer diameter of the clad fiber

• The two fiber ends are then pushed into the capillary until they meet. Compression or friction usually holds the fibers in place.

Rotary or Polished-Ferrule Splice• More elaborate type that can compensate for subtle differences in the fibers

being spliced

V-Groove Splice• Useful in multifiber splicing of ribbon cables where each parallel fiber slips

into a separate groove. Special splicers are sold for this purpose

Elastomeric Splice• Has an internal structure similar to that of a single fiber v-groove

splice

• The plates are made of a flexible plastic held in a sleeve, and the groove is tapered toward the center.

Reusable Splice• A mechanical splice in which the fibers are clamped in place but not

glued

QUESTION #2:

WHAT ARE THE STEPS INVOLVED WHEN USING A FUSION SPLICER?

SPLICING REQUIREMENTS

FUSION SPLICING

• Normally performed by technicians who work primarily with fiber (installing new cables or repairing existing ones)

• Used mostly for cables with long outdoor runs, where loss is a major concern

MECHANICAL SPLICES

• Mostly used by non-specialists

• Used to repair shorter cables, indoors where fixing the cable is more important than its final loss

• Mechanical splicing is more expensive per splice but the overall cost is lower than that of a fusion splicer

Splice housing

• Splice housings organize spliced fibers in multifiber cables, and protect them from strain and contamination

• Fiber-optic splice cases are put in places where splices are necessary: manholes, utility poles, places where fiber cables enter buildings

• Fiber splice enclosures are designed with many specifications. A few include:• Hold cable strength member tightly• Block entrance of water• Provide redundant seals in case one level fails• Be re-enterable if the splice needs to be changed or repaired• Organize splices and fibers so they can be readily identified• Provide room for initial splicing and future modifications

QUESTION #3

WHAT ARE SOME SPECIFICATIONS THAT FIBER ENCLOSURES ARE DESIGNED TO INCLUDE?