5 Pro Tips to Help You Understand Fiber Optic Cable Better

1.Understand the Structure of an Optical Fiber

An optical fiber typically consists of three layers: the core, cladding, and coating. The core and cladding are different refractive indices glass.

The core is high-refractive-index glass (doped silica), while the cladding is low-refractive-index silica glass (pure silica).

Light enters the fiber at a specific angle and undergoes total internal reflection at the core-cladding interface, enabling it to propagate through the fiber. The coating layer protects the fiber from external damage and increases its flexibility.

2. Know the Composition of a Fiber Optic Cable

A fiber optic cable contains optical fibers, which are thin, fragile glass fibers. To protect the delicate fibers, they are encased in plastic protective tubes and an outer plastic jacket.

The combination of optical fibers, protective layers, and additional components forms a fiber optic cable. While optical fibers are the core part of a fiber optic cable, the terms “optical fiber” and “fiber optic cable” are not interchangeable.

3. Understand Dispersion in Optical Fibers

Dispersion in optical fibers refers to the distortion of signals caused by the different transmission speeds of various frequency and modal components.

There are three types of dispersion: material dispersion, waveguide dispersion, and modal dispersion. Material and waveguide dispersion occur when the signal is not a single frequency, while modal dispersion occurs when the signal is not a single mode.

Single-mode fibers only have material and waveguide dispersion, while multi-mode fibers also experience modal dispersion. Dispersion affects the transmission capacity and limits the repeater spacing in fiber optic communication systems.

4. Identify the Causes of Attenuation in Optical Fibers

The main causes of attenuation in optical fibers include scattering, absorption, bending, compression, and power loss at connectors and splices.

Attenuation is measured in dB/km, representing the loss of signal power per kilometer of fiber. Rayleigh scattering and intrinsic absorption are inherent losses in optical fibers.

Additionally, losses can also occur at fiber connections due to misalignment, non-perpendicular end faces, uneven end faces, mismatched core diameters, and poor splicing quality.

5. Know the Core Sizes of Optical Fibers

The core size refers to the physical dimension of the fiber’s core. Multi-mode fibers have core sizes ranging from 7μm to 3mm, with the most common being 50μm, 62.5μm, 100μm, and 200μm.

The industry standard for data communications is 50μm and 62.5μm multi-mode silica fibers. Single-mode silica fibers typically have a core size of 8.3μm.

Plastic optical fibers have core sizes ranging from 0.25mm to 3mm, with 1mm being the most popular.