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Difference Between Primary Coated Fiber, Secondary Coated Fiber and Ribbon Fiber

November 20,2021

Optical fiber is used on the transmission of optical fiber, that is, data and signal transmission using optical fiber as the medium. Optical fiber, not only can be used to transmit analog and digital signals, but also can meet the needs of video transmission. The data transmission rate of a single optical fiber can reach several GBPS, and the transmission distance can reach tens of kilometers without the use of repeaters.

Fiber optic is an extremely convenient tool for transmitting signals, cable which a slim optical pistil, can replace more than thousands of physical communication lines, to complete a large number and long-distance communication work.


Fiber optic transmission of 8 advantages are as follows.

High sensitivity, not subject to electromagnetic noise interference.Small size, light weight, long life, low price.Insulation, high voltage, high temperature, corrosion resistance, suitable for special environmental work.Geometry can be adjusted according to environmental requirements, easy signal transmission.High bandwidth, high communication volume, small attenuation, long transmission distance.Small signal crosstalk, high transmission quality.High confidentiality.Easy to lay and carry raw materials.

So, how does the fiber optic have the above significant advantages?

Optical fiber is composed of glass by the internal total reflection to transmit the optical signal. The standard diameter of the glass fiber is 125 microns (0.125 mm), the surface is covered with a protective coating of resin 250 microns or 900 microns in diameter. The central part of the glass fiber that transmits light is called the “core” and the surrounding cladding has a lower refractive index than the core, thus limiting light loss.

The quartz glass is very fragile and is therefore coated with a protective coating. There are three typical types of optical fiber coatings.


Optical fiber coated with a 0.25 mm diameter UV-curable acrylic resin coating. This is very small in diameter, increasing the density of fibers that can be accommodated within the fiber optic cable, and is very commonly used.


Also known as tightly wrapped buffer layer fiber or semi-tightly wrapped buffer layer fiber. The fiber is coated with a 0.9 mm diameter thermoplastic resin. Compared with 0.25 mm fiber, it has the advantage of being stronger and easier to handle. It is widely used in LAN cabling and fiber optic cables with a small number of fibers.


Ribbon fiber improves the efficiency of connector assembly and facilitates multi-core fusion splicing, thus increasing operational efficiency.

Ribbon fiber optic cable is a fiber optic cable processed from multiple single fibers by coloring, stacking into ribbons and secondary sheathing of the fiber ribbon as a unit. There are two types of fiber tapes, i.e., encapsulated and edge-bonded, the former can withstand lateral pressure, the latter is thinner. Each tape can have 4, 8, 12 or 16 fibers in different colors, with a maximum of 1,000 cores.

The fiber surface is coated with UV-curable acrylic material, which can be easily removed with standard fiber stripper pliers to facilitate multi-fiber fusion splicing or removal of individual fibers. With the multi-core fusion splicer, ribbon fibers can be fused in a single pass, making it easy to identify a large number of fibers in a fiber optic cable.

Ribbon fiber spacing of 0.28mm (for 4, 8) and 0.3mm (for 12 and 16), neatly arranged, flatness in the vertical direction, that is, deviation requirements, shall not be greater than, for example, 30, 40, 50um (depending on the number of fibers in the ribbon), in order to facilitate clustering (fusion splicing) splicing. Orderly use of chromatography in the band fiber, to facilitate maintenance and splicing identification without error. The small size of the fiber optic tape can improve the fiber optic cluster density in the fiber optic cable, can constitute a large number of cores, such as 320 until 3456 cores. Suitable for the current rapid development of fiber optic access network.

Translated version)