Chapter 5: How to choose the right optical fiber cable

Parameters

General outline of the parameter involved in choosing the rigth optical fiber cable design.

First parameter: the optical fiber

The four most common types of fiber in fiberoptic networks today (no specific order).

Primary coating

Application of acrylate as the primary coating.

Acrylate as the primary coating

Primary coated fiber.

The fiber characteristics after primary coating application

The most common geometrical parameters for standard single-mode fiber 8–10/125 μm.

Maximum permissible stresses on a primary coated fiber.

Color-coding for optical fibers

Color-coding scheme used by Telia AB, Sweden.

Second parameter: the buffers

Loose tube buffer (loose fibers/ribbons in tube)

A number of primary coated fibers or ribbons can lie loosely in a tube, which functions as a loose tube buffer.

Temperature variations

The fibers can move freely within the loose tube buffer to compensate for temperature variations.

Areas of application for tight buffered fibers

Fiber with tight buffer.

Tight buffered fibers

Fiber ribbon technique: Encapsulating

The three most common methods of manufacturing fiber ribbon.

Encapsulated ribbon fiber

Manufacture

Encapsulated fiber ribbon. The illustration shows a fiber ribbon with one layer of acrylate applied over primary coated fibers.

Tests

Macrobend test

Setup for macrobend test.

Torsion test

Setup for torsion test.

Crush test

Setup for crush test.

Process testing

Strippability - random testing

Example of good strippability (upper) and bad strippability (lower).

Separability - random testing

Each individual fiber must be able to separate without damage to the individual primary coatings.

Fiber curl

Fiber curl.

Attenuation

Graphs showing OTDR attenuation plot at both 1310 nm and 1550 nm.

Geometry

Geometry of a four fiber ribbon.

Parameters regarding the geometry of the fiber ribbon.

Third parameter: the strength member

Aramide yarn

Different types of strength member.

Fourth parameter: the cable core

Cables with circular core

Optical fiber cable, concentric construction, with loose tubes around the central strength member.

Cable illustrated is the GRHLDV.

Optical fiber cable; concentric construction with tight buffered fibers around the central strength member. Cable illustrated is the GNHLBDUV.

Cable with slotted core

Slotted core profiles. From left to right S, Z and SZ stranding.

Three different types of slot profile.

Pitch of a slotted core cable

Fibercreep due to temperature changes.

Expansion and contraction of cables

The fiber can move freely.

Expansion and contraction caused by temperature variations

Young's modulus, density and coefficient of linear thermal expansion of various materials used in optical fiber cables.

Four examples of optical fiber cables with slotted core. Cables illustrated are from the left: GRSLDV, outdoor cable with loose tube buffer.

GNSLBDV, indoor/outdoor cable with tight buffered fibersGASLDV, outdoor cable with four fiber ribbon

GASLDV, outdoor cable with eight fiber ribbon.

Optical fiber cable without a core

The simplest optical fiber cable design is suitable for connecting cables and in data

networks. The cable illustrated is GNLBDU.

With a multiple of subcables and an extra sheath, this cable becomes a neat package of 24 GNLBD cables measuring only 15 mm in

diameter. The cable illustrated is GNHLLBDU.

Fifth parameter: the water protection

Metallic tube: Copper encapsulation

Copper plate formed to a tube and electrically welded to a water-proof encapsulation.

Sixth parameter: sheathing

The sheath has primarily the following functions:

• Provides mechanical protection

• Provides thermal insulation

• Protects against chemicals

• Provides moisture protection

• Protects from rodents.

The plastic materials normally used for the sheath are:

• Standard polyethylene (PE)

• Flame retardant halogen-free materials

• Polyvinyl chloride (PVC)

• Polyamide (PA)

• Fluoroplastics

• Polyurethane (PU)

• Copper tube (Cu)

Applying the final sheath:

Seventh parameter: extra reinforcement

Corrugated steel tape

Corrugated steel tape-reinforced cable for laying underground, or in ducts. The cables illustrated are GRSLWLV and GASLWLV.

Steel wire, steel tape

Steel-reinforced cable for laying underground, e.g., by direct ploughing. The cable illustrated is GRSLTLV.

HET - heat expandable tape

By using dielectric reinforcement, a completely metal-free cable can be manufactured for direct ploughing or laying underground. This cable is ideal for installations located in the

vicinity of high voltage lines. The cable illustrated is GASLLDV, 192 fibers.

Aramide yarn

Aramide yarn is used as longitudinal reinforcement in aerial cable for spans up to

250 m. The cable illustrated is GRLSDV.

Aerial cable with a large amount of of aramide yarn as strength member. This type of cable is self suporting for spans up to 1 000 m. Cable

illustrated is the SkyspanTM (Focas Inc.).

Suspension strands

With a steel suspension strand, optical fiber cable can be suspended in spans of 50 - 70 m. The cable illustrated is GASLCV.

Optical ground wire, OPGW

Optical power ground wire to replace the traditional ground wire on topof power lines. Cable illustrated is thr SkyliteTM (Focas Inc.).

Hybrid cables

Two examples of hybride cable designed to be installed alongside the railway tracks.

A collection of newer types of cables

Cable to be wrapped around ground wire or phase line

”Skywrap“.

Indoor cable with fiber ribbon, suited for FTTH etc.

Outdoor cable with loose tube suited for FTTH etc.

Ribbon cable with 432 fibers.

Ribbon cable with 864 fibers.