Introduction to various types of cables: optical cables

Component

Materials and functions

Fiber core

High purity silica (diameter 9 µ m single-mode/50 µ m multimode), optical signal transmission channel

Cladding

Refractive index lower than the fiber core, utilizing the principle of total reflection to constrain the optical signal

Coating

Acrylic resin protective layer to prevent fiber optic micro bending damage

Reinforcement

Aramid yarn or metal steel wire, tensile strength (tensile strength ≥ 1000N)

Sheath

PE/PVC/Flame Retardant Material, moisture-proof and corrosion-resistant (outdoor type with armor layer)

Cable core structure

Structural features

layer stranded

Several secondary coated optical fibers are twisted around the central tensile member using a loose sleeve structure with one tube multi fiber technology. The optical cable can have up to 144 cores, and using multi fiber tapes instead of fiber bundles can have up to thousands of cores.

skeleton type

Squeeze a plastic skeleton outside the tensile element, and embed optical fibers into the skeleton groove. Each groove can hold one or more optical fibers or fiber ribbons, and the fibers entering the groove should have a suitable surplus length. The optical fibers of this structure's ribbon cable can reach thousands of cores.

Central tube type

Fill a PBT tube with adhesive paste and place 8 groups (12 optical fibers per group) of 96 optical fibers. Up to 216 optical fibers can be used with fiber ribbon.

Unit type optical cable

First, several optical fibers are twisted into fiber units in a layered or skeletal manner, and then each unit is twisted together. Currently, optical cables are developing towards dense and large fiber count direction, and it is expected to reach 4000 cores in the future.

Usage environment

Use features

Directly buried

Directly buried underground, with waterproof and armor layers, used for long-distance communication.

The Conduit

Laying pipelines or tunnels with aluminum strip PE composite layer, used for local or long-distance interruption.

Overhead

Additional lightweight metal armor layer, used in provincial trunk or regional communication lines.

Indoor

It should have flame retardant properties (low smoke and halogen-free) for use in local area networks within buildings or as indoor entry lines for outdoor optical cable lines.

Inside the device

Lightweight single core or dual core optical cables for connecting optical paths within equipment.

Flexible optical cable

Fiber optic cables require flexibility, small size, light weight, good flexibility, and sufficient tensile strength, suitable for non fixed applications and military mobile communications.

Underwater

Good radial and longitudinal sealing performance is required, with steel wire armor for use in communication line crossing river areas.

Seabed

The optical cable core and tension resistant components should be carefully designed to withstand water pressure up to 80MPa, tension resistance of 80KN, DC resistance of 0.4 Ω/km, and a maximum power supply voltage of 6KV. They should be designed with a loose sleeve structure and wrapped with two layers of steel wire outside the loose tube.

Optoelectronic integrated cable

The cable contains an 8-core optical fiber unit, 7 copper wire four wire groups, and 9 symmetrical wire pairs, used in railway communication systems. The optical fiber is used for high-capacity communication on the main line, and the four wire groups and wire pairs are used for interval communication and signal transmission on the railway.

Fiber optic composite power cable

Fiber optic cables are placed in the gaps between three-phase cable cores to form composite cables, which can transmit power and achieve data communication without induction or crosstalk.

Fiber optic composite overhead ground wire (OPGW)

Combining the excellent characteristics of optical fibers and aluminum clad steel wires to form high-performance cables that can be used for both communication and ground protection;

In addition to meeting the communication needs of power production scheduling and power system automation, it can also provide communication services for cable television, public security systems, banking systems, and postal and telecommunications systems to the society, especially on newly built lines of 220KV and above.

All medium self-supporting optical cable (ADSS)

ADSS is used on 35-110KV power lines, utilizing existing power towers to support and install along the poles near the power lines. Fiber reinforced plastic FRP is used as a reinforcement in the center of the optical cable, and multiple strands of aramid yarn are placed inside the sheath as reinforcement material.

Index

Typical values

Testing standards

Attenuation coefficient

Single mode: 0.36dB/km@1310nm

ITU-T G.652.D

Bandwidth

Multimode: 4700MHz·km@850nm（OM4）

ISO/IEC 11801

Tensile strength

≥ 2000N (outdoor armored type)

GB/T 7424.2-2008

Bending radius

Static ≥ 10 x fiber optic cable diameter, dynamic ≥ 20 x diameter

IEC 60794-1-2

Characteristic

Optical cable

Copper cable (Cat6A)

Bandwidth

100Gbps+(single-mode)

10Gbps (within 100m)

Distance

100km without relay+

≤ 100m (10 Gigabit Ethernet)

Immunity

Immune electromagnetic interference

Require shielding layer (STP)

Safety

No radiation, difficult to eavesdrop on

Electromagnetic leakage risk

Cost

The equipment is expensive, but the operation and maintenance costs are low

Easy deployment, high cost-effectiveness for short distances