What Is Fiber Optic Cable Ultimate Guide

Fiber optic cables typically have a service life of over 20 years (or over 30 years in static conditions) with a warranty period ranging from 12 to 18 months. For high-quality fiber optic cables, consider Fibconet, which offers a wide range of cables for various applications.
Table of Contents

Fiber optic cables are an essential part of modern communications infrastructure.

It is an assembly similar to an electrical cable, but containing one or more optical fibers to carry light. The carrier of optical fiber communication is infrared light.

Understanding these knowledges is crucial for efficient network design and optimal performance, especially for your business.

1. Working Principle Of Optical Fiber

Optical fiber transmission is carried out by the mechanism of total reflection of light.
Light in the same medium is transmitted in a straight line when the two media refractive index is not equal to the phenomenon of total reflection.
If the light refraction, it will cause signal loss.

2. Comprehensive Classification of Optical Cables

Optical cables, also known as fiber optic cables, can be classified based on a variety of factors such as their application environment, structure, construction method, and number of fiber cores.

Classification Based on the Application Environment

  • Outdoor Cables: Designed to withstand harsh environmental conditions, these cables are armored or encased in a robust outer sheath for durability and resistance to physical damage. They can endure temperature changes, moisture, and UV exposure.
  • Indoor Cables: Designed for indoor environments like office buildings, data centers, and residential areas, these cables are flexible and easier to negotiate around corners. They often feature flame-retardant jackets to comply with fire safety standards.
  • Drop Cables: These cables are specifically designed for last-mile connectivity, connecting the telecommunication network to individual homes or buildings. Commonly used in fiber-to-the-home (FTTH) installations.

Different cable structures are used for different applications:

  • Butterfly Cable: Includes optical fiber G657.A1/A2, strengthening parts, and a Low Smoke Zero Halogen sheath.
  • Circular Lead-in Cable: Comprises Optical fiber G657 B3 or A1/A2, aramid reinforcement, and a sheath made of LSZH or TPU.
  • B3 Cable: Uses expensive TPU material, noted for hydrolysis resistance, friction resistance, chemical resistance, and good bending performance.

Classification Based on Structure

Optical cables can be divided into three main types based on their structure:

  • Center Tube Type
  • Layer Twisted Type
  • Frame Groove Type

The main structural components are:

  • Fiber Core: This is the light-transmitting part of the fiber, which may be single-mode or multi-mode. It has a high refractive index and is typically 9-10 µm for single-mode and 50 or 62.5 µm for multi-mode fibers.
  • Cladding: This layer has a lower refractive index to allow total internal reflection. Its diameter is generally 125 µm.
  • Coating Layer: This layer protects the fiber core and cladding, enhancing the mechanical strength. It usually consists of two layers, a soft inner coating and a harder outer layer. The overall diameter is usually 245 µm.
Optical Fiber

Classification Based on the Construction Method

  • Overhead Cables: These include self-supporting cables (like 8-figure cable, ADSS, OPGW) and non-self-supporting cables (like GYTS and GYTA53).
  • Underground Cables: These are subdivided into pipeline and direct burial cables. Pipeline cables (such as GYTA) lay emphasis on moisture resistance, while direct burial cables (like GYTA53) have a steel sheath and are buried directly in the ground.
  • Submarine Cables: These are special cables designed for underwater applications, used for transmitting telecommunication signals across oceans and seas.

Optical Fiber Types

Optical fibers can be Single Mode (SM), G657 series, or Multi-mode (MM):

  • SM G652D: Mainly used for indoor single/double and outdoor mainline construction.
  • G657 Series: Distinguished by varying bending performance, with A1,2 primarily used for butterfly cables and leather cables.
  • MM OM1~5: Mainly used for indoor cables, with coloration standard for jacket color.
multimode fiber

3. Tips of Fiber Optic Cable

Reinforcement Pieces

Reinforcement pieces usually use metal (steel wire, steel strand) or non-metal (FRP, aramid yarn, glass yarn).

The choice of reinforcement piece depends on the need for corrosion resistance, the need for adhesion to prevent slipping, and the cost.

Strain and Tension

Strain divides into fiber strain and cable strain, and the test has specific national and domestic standards, such as GB/T.

The tension is strong and the strain is small (it is difficult to stretch the length), which is less than the strain of the optical fiber, so it plays the role of protecting the optical fiber.

Flame-retardant features

High-priced flame-retardant materials, such as aramid yarn, burn out on their own and turn to dust when burned.

Low-priced non-flame-retardant materials, such as polyester yarn, will shrink when burned and continue to burn.

Bending Performance and Tensile Resistance

Fiber optic cables are more prone to breaking due to poor bending performance rather than low tensile resistance.

It’s important to handle these cables carefully to avoid damaging them, especially when they are bent during installation or use.

Use of Single-Core and Twin-Core Fiber Optic Cables

Indoor vertical use branch internal single-core fiber optic cables are prevalent because vertical wiring requires more pushing force.

Single-core and twin-core fiber optic cables, such as those with diameters of 0.9 mm, 2.0 mm, and 3.0 mm, are often used for indoor patch cables.

fiber optic cable

Joint Requirement and Fusion Process

Indoor optical cables typically require a joint. The tight set of the coating layer often has a diameter of 0.9 mm. Outdoor optical cables usually undergo a fusion process, which also requires peeling of the coating layer.

The fiber box provides a slot for welding, known as the fusion disk.

Color-Coding of Optical Fibers

Optical fibers are usually color-coded to facilitate identification, especially in multi-core configurations.

The colored fibers are generally arranged by spectrum, with some variations such as mixed arrangements in specific regions like Brazil.

The coloring not only protects the optical fiber but also aids in identifying it, facilitating docking construction.

4. The Advantages Of Using Fiber Optic Cable

  • Wide frequency band, large communication capacity. 
  • No crosstalk interference.
  • Low loss, long relay distance. 
  • Small size, light weight. 

Anti-Rodent Measures Introducing

Fiber optic cables, while offering significant benefits in terms of high-speed data transmission, are vulnerable to physical damage, including rodent bites.

Over the years, various methods which mean to prevent this type of damage, each with its own advantages and drawbacks.

Chemical Repellents

One of the earliest methods involved mixing chemical substances into the cable materials. These chemicals were volatile and designed to deter rodents with their scent or taste.

However, this approach was not environmentally friendly and has mostly been phased out due to potential health and environmental hazards.

Glass Yarn and Glass Belt

Another anti-rodent method involves the use of glass yarn or glass belts in the cable construction.

These materials have very high requirements for equipment to be effectively incorporated into the cable structure.

When a rodent attempts to bite through these cables, the glass components can become tangled in the rodent’s mouth, serving as a deterrent.

However, this method provides only symbolic rodent protection and may not be fully effective against persistent rodent attacks.

Hard Sheath Materials

The most effective and commonly used anti-rodent method today involves constructing the cable sheath from hard materials such as steel or nylon.

These materials are much harder for rodents to penetrate, providing a high level of protection against rodent bites.

This method is currently widely adopted due to its effectiveness and minimal environmental impact.

5. Installation Process for Indoor Optical Cables

The installation process for indoor optical cables typically includes the following steps:

  1. Interlacing the Core: Unraveled the core of the cable to prepare for the next steps.
  2. Peeling the Coating Layer: Stripping off the protective coating layer to expose the optical fibers.
  3. Cleaning with Alcohol: Carefully clean the exposed fibers with alcohol to remove any debris or residue.
  4. Re-Interlacing the Core: Re-interlaced the core, ready for connection.

Maintaining a stable size and superior quality ensures smooth operation when interlacing and helps avoid problems caused by incorrect sizes.

Optical Fiber Cable Machine
Optical Fiber Cable Machine

6. Fiber Optic Cable Manufacturing

Cable Model Indicators

  • GY: This code means outdoor cables, also known as field cables.
  • GJ: This code means indoor or intra-office cables.
  • GJY: This code means indoor and outdoor cables, also known as introduction cables. These can further divide into butterfly cables, circular cables and figure-8 cables (a double circular structure with the upper layer used for tensile strength, generally reinforced with steel strands).

Material Indicators

  • Center reinforcement: If placed centrally, metal is generally omitted, while non-metal will add an ‘F’.
  • Waterproof material: Dry types are generally omitted, and refer to water blocking yarn, water blocking belt (wrapped), and water blocking powder. ‘T’ refers to oil paste filling, divided into fiber paste (directly contacts the optical fiber, requires higher quality, more expensive) and cable paste.

Sheath Material

  • PE: Used for the jacket of outdoor cables.
  • PVC: Used for tight packaging or tight sleeve, and the outer sheath of 2.0 mm or 3.0 mm cables. Especially used for mining cables due to its flame retardant properties.
  • LSZH: Used for the outer sheath of indoor and outdoor cables.
  • Nylon: Generally used for tight or anti-rodent outer sheath (a layer of PE sheath outside, 0.5mm, more expensive).
  • TPU: Comes in two types – polyester (cheaper, poor hydrolysis performance, prone to cracking outdoors, not recommended for cable use) and polyether (mainly used for cables).
  • PP: Used for filler ropes, commonly referred to as ‘false cable’ for indoor cables.
  • PBT: Used for loose casing, generally used outside.

Lifespan and Warranty

Fiber optic cables typically have a service life of over 20 years (or over 30 years in static conditions) with a warranty period ranging from 12 to 18 months.

For high-quality fiber optic cables, consider Fibconet, which offers a wide range of cables for various applications. Contact us for more information!

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