This is how glass, the light transfer part of an optic fiber cable, is used to make a fiber core. How it’s made, explained in simple terms in case you do not know about fiber cores. 

For most people, fiber core is a different kind of electric cable that is made for long-distance data networking. 

But have you ever stopped and thought, what is the manufacturing process of fiber core? Why is it used in telecommunications instead of cables made of wires? What makes it send data over long distances? 

Unless your cable usage is limited to regular wires, fiber cores are high-performance cables you should try out.

But how exactly is fiber core made? 

The fiber core is made of plastic or glass. There are cases where other components are used. But, it depends on the transmission range needed. 

The glass makes it a crucial part of the fiber, to transfer light. 

Want to know more about the manufacturing process of fiber core? Sit back, relax and read further. It will be clear enough for easy comprehension.

What Is Fiber Core

An optical fiber comprises three fundamental concentric components. They are: 

• The core

• The cladding 

• The coating or jacket

Fiber core is the minor part of optical fiber which transmits light. However, being the smallest part doesn’t make it less important. It is the most significant part of an optical fiber. 

According to a Harvard lecture-demonstration: 

The Light conveyed by a bundle of optical fibers is possible due to the presence of fiber cores. 

The major element of a fiber core is glass. Although some production processes involve using plastics, glass is prevalent. There are instances where the production entails using other elements. 

But, it depends on the range of transmission that the optical fiber light needs. As the core’s primary duty is to transport light to the optical fiber. 

As a crucial component, even though its make is comparable to that of the cladding. The index of refraction is lower, (with a difference of 1%). 

This index difference is noticeable along the length of the fiber. As it prompts inner reflection to appear at the index boundary. 

Upon the transmission and appearance of light on the fiber. The core makes it not escape nor bypass via the sidewalls. 

The glass that makes the core causes easy transmission of light. 

It comprises only authentic silicon dioxide(SiO2). 

Glasses that comprise this component are usually very clear. If you take a look at it from a 5 to 6 miles angle, it will look as though you are viewing through your home window. 

Also, germania and phosphorus pentoxide(or alumina) is the main dopants used in the production process. They help to curb an uncontrollable rise of the refractive index during production.

The manufacturing of fiber cores is for different applications. To determine this, different diameters must be in use to get it right. The fiber cores made of glass range from 3.7um to 200um. 

Optic fibers used in telecommunications comprises three fiber core types: 

9um, 50um, and 62.5um 

Optical fiber types are dependent on core size. The two types which are single-mode and multimode fibers contain different cores. 

The single-mode fiber is made up of 8 to 10 microns of cores. This makes the transmission of light gear in a single wavelength. The light transmits to the middle area of the core. 

Then the multimode fiber sometimes consists of a plastic core. The range of microns in the core is usually 50 to 62.5.  It is much bigger than a glass. 

A typical plastic core range is 980um. 

Background Analysis 

At the mention of optic fiber cables or fiber core, we think of telecommunications. This isn’t far from the truth. However, there’s more to its invention. 

Fiber core wasn’t present at the development of the first telephone. The first American telephone inventor, Alexander Graham Bell didn’t use it. While his first attempt at communication in 1880 involved light. Fiber core was not in use, so there was a limit to telephone communication. 

During the 1880s, while telephones were being worked on, the use of light was present. But, the distance was far shorter than it was in the mid-twentieth century. 

The mid-twentieth century was the advent of lightwave communication. It aided the provision of communication sources through the help of advanced technology. All these were possible through the provision of:

• The laser

• An advanced medium 

• The optical fiber 

The Laser

This was developed in 1960 when limited lightwave communication was still in use. It came into use due to the advent of an advanced technology that began in the mid-twentieth century. 

The Advanced Medium and Optical Fiber

The advanced medium was discovered 6 years later after the laser was invented. During this time, England researchers found out that light waves can be transmitted. The transmission was through silica glass fibers, and there was no signal loss. 

Four years later(in 1970), the formulation of a new type of laser took place. It was during this time that the commercial production of optical fibers began. 

Consequently, optical fiber production became the key player in the communication system. It is a hair-fine filament that is drawn from molten silica glass. This glass is the fiber core, usually single.

The Replacement of Metal Wires

Fibers have gradually become the main element in the telecommunication industry. Metal wires are obsolete because optical fibers are very high in capacity and speed. 

Also, they cannot meet the demand for fast communication. As it involves the transformation of information into light via the core of the optical fiber. 

Presently, fiber optic cables are used worldwide for telecommunications services. The American telephone companies exemplify this technology. Because the transmission nature is perfect for power lines and accessing computer networks. 

In the fiber-optic transmissions system, fiber cores connect data links that comprise lasers and light sensors. 

To transmit communication, a data link transforms analog electronic signs. This can be through the production of a video camera or a television discussion. It transforms it into laser light or digital rhythms. 

As all of these travel, the optical fiber aids it to move to other data links where a light sensor remodifies them into an electronic signal.

Raw Materials/Components

Silicon dioxide is the main component of optical fibers. Although insignificant proportions of chemicals are usually added. 

Here are other components and it’s used: 

• In the present outmoded crucible production technique, highly purified silica in powder form was utilized. 

• The major source of silicon for the vapor deposition process presently in universal use is the liquid silicon tetrachloride(SiCI 4) which is in a gaseous surge of pure oxygen(02). 

• Chemical compounds used to make fiber cores are germanium tetrachloride(GeCI 4) and phosphorus oxychloride (POC1 3). Asides from their specific function to optical products, they are in use to make outer shells or cladding of the fiber. 

The most important feature of a fiber core is the chemical makeup and purity of glass used during its making. It also affects the degree of fading. 

That is why research is more concentrated on assembling glasses with the most outstanding level of purity. 

To get a transparent core that has almost the entire range of noticeable light frequencies, one needs to pay careful attention to the glasses. As it helps to improve the optical fiber performance. The perfect glass for these are glasses with high fluoride capacity. 

Generally, good glasses are very beneficial for multimode optical fibers. They help to convey many discrete lightwave signals together.

A cladding of different glasses or plastic is the main resource of a fiber core. 

Other materials which may be present are fluorozirconate, chalcogenide glasses, and fluoroaluminate. 

Additionally, crystalline elements like sapphire are also utilized. As they add to longer wavelength technical applications like infrared. 

The Design

While the core and cladding of fiber optic cable may look similar, the designs differ. In a fiber core, many single optical fibers are fixed jointly around a primary high-strength plastic carrier. In many cases, steel cables are used for support. 

Materials used for the protecting layers of the core are kevlar, aluminum, and polyethylene. 

To design an optical fiber, coatings of silicon dioxide are the first placement. A hollow subtract rod is used, and the silicon dioxide is then placed on the inward surface.

The process is performed via a modified chemical vapor deposition. This involves the incorporation of different chemical vapors mixed with a gaseous surge of pure oxygen, which is then applied to the rod. 

As the gaseous surge touches the heated surface of the rod, the inside begins to form a glassy residue. This glassy soot is usually many layers thick inside the rod.  

As the glass residue piles up to the thickness needed, the substrate rod is shoved through other hot stages. This helps to expel any bubble, vapor, or moisture present in the heated soot layers. 

Do note that as the substrate rod is heating, the inward soot coating thickens to form the boule. Otherwise known as preform of highly pure silicon dioxide. 

How Fiber Core is Made

A highly purified silica glass is the main component of the fiber core. The production of fiber cores are of two types, which are: 

1. The crucible Technique: this has to do with melting powdered silica. Which then generates multimode fibers which are fatter and appropriate for short-distance communication of various lightwave signals. 

2. The Vapor Deposition Technique: this is mostly for long-distance transmission. During this process, a solid cylinder of core, including a cladding material is created. Which is then made hot and drawn into a single-mode fiber, it is very thin. 

The vapor deposition technique is the commonly used fiber core production method. There are three kinds of it, which are: 

1 Outer vapor phase deposition

2. Vapor phase axial deposition

3 Modified chemical vapor deposition

The modified chemical vapor deposition(MCVD) is the most suitable for contemporary communication needs. It produces a low-loss fiber which is highly efficient for long-distance cables. 

The Modified Chemical Vapor Deposition Process

First, the deposition of layers of specially formulated silicon dioxide is made to form a cylindrical preform. This is done on the inner surface of a hollow substrate rod. 

These layers are deposited by adding many chemical vapors e.g germanium tetrachloride(GeC 4), silicon tetrachloride(SiCI 4), including phosphorus oxychloride(POC1 3).   They are added to the gaseous surge of pure oxygen. 

There is a flame under the rod that makes the wall stay extremely heated. During this process, highly pure silicon dioxide is formed. It results in a very thick glassy soot which is then deposited to the internal area of the rod.  The deposited glassy soot eventually becomes the core. 

Let’s move further to find out how.

To protect the coating formed, various protective layers are added. The severity of the environment where the cable will be installed determines the level of protection. 

 This protection is done via heating to solidify and form the preform. This boule or perform measures:

10 – 25 millimeters(.39 to 98 inch) in diameter. 

The length is usually 600 to 1000 millimeters. Which are 23.6 to 39.37 inches. 

Next up is the process of drawing the fibers

The solid preform obtained from the process above is transported automatically to a vertical fiber drawing operation. 

The vertical drawing system or operation are machines that can make continuous fibers. They are usually two stories high and can make up to 186 miles (about 300 kilometers) of continuous fibers. 

The vertical drawing system comprises a furnace to help dissolve the edge of the preform. It also has sensors to control the production of fiber, especially the diameter being dragged from the preform. Additionally, it has coating devices that act as protective coatings over the external cladding.

Just like a leaky faucet drops to water, the gob at the preform’s end falls. Upon falling, the preform already has optical fiber inside which is then brought out.  As the optical fiber is drawn out of the heated preform, the element in the initial substrate rod sets the cladding. 

Now the silicon dioxide deposited earlier on (as soot), is what forms the core of an optic fiber. 

That is not all there is because as the fiber is pulled out, there is a need to measure its circularity. For accuracy, measuring devices are used to monitor the diameter. While other equipment applies a protective coating. 

Finally, before it’s wound on a spool, a measuring device monitors the diameter. This happens as it goes through a corrective furnace. 

Quality Assurance 

Note: All of these processes are for information purposes. If you are interested in an optical cable production business. You can contact our experts for a free consultation and quotes. 

Our experts can manufacture an optic cable machine, tailored to your business needs. With our cost-efficient offers and ready to help experts. Undertaking a business deal with us is worth it. 

Quality Control is crucial in fiber optics production. Attention to detail is needed, starting from the chemical compounds supplier to specialty suppliers. 

The raw material used for making fiber core such as substrate rods, protective fiber coatings, and chemical reactants needs to be checked. Computerized on-stream analyzes can be employed. It can be connected to the process vessels so it can check the constituent compounds. 

This process involves the expertise of engineers and trained and certified technicians. As fibers are pulled out and the production of preform ensues. A professional close watch is needed to oversee the sealed vessels. 

Also, there is the automatic management of high temperatures and pressures during the manufacturing process. Computers are set by experts to operate and effectively manage complicated process schemes.  

The fiber diameter is continuously monitored by a detailed measurement mechanism. This device also delivers a response that aids to control the pulling process of the fiber. 

Functions of Core in Optical Fiber

The core is more like a medium in the fiber optic cable. The light a fiber optic produces goes through the core. This is after a cumulative inward reflection. 

The core also preserves light energy. As light passes through the middle of the fiber. It goes through millions of reflections, the core walls protect it during this process. 

Upcoming Development 

There is still continuous research concerning the future of optical fibers. However, it is based on improving optical properties. 

Presently, the most promising form for optical fiber is the one with cores made out of silica glasses. It is going to be highly efficient, containing an increased fluoride content. 

In addition, there is also a decrease in loss experienced during production. When compared to before, the present average loss you’ll experience when drawing from glass is 0.005-0.008 decibels per kilometer. Unlike earlier fibers with losses ranging from 0.2 decibels per kilometer. 

There is also an increase in the use of highly sophisticated processes during production. Now increased energy lasers are used to dissolve the preform before the fiber draw. 

With the increased demand in technology and fast growth of the telecommunication industry. The fiber optics production process is set for a fast win. 

Last Words 

We’ve cleared up the technicalities of fiber core production in clearer terms. Now you know what a fiber core is, the important component, and the insignificant materials.  If you intend on making fiber optic cables, the experts at Hongkai are your best bet for guidance and better production line purchase. Feel free to call or email for a free consultation.