How Fiber Optics Is Made

It often surprising that we have several contrivances for everyday use yet ignorant by large on how they operate. That is highly true with regards to fiber optics; hitherto we are more predisposed of clunking faulty receivers who ‘garbled’ voices over the phone and not even considering how the fiber optic material may not attenuate signals as clearly.

Fiber optics is complicated science, and how fiber optics is made is much more so. Hopefully by explaining the fundamental concepts on how fiber optics is made readers could understand how the system truly works.

By the way, the term fiber optics is an often misused term. Fiber optics cannot be used to call the device employed; rightfully it is called optical fiber. Fiber optics instead is a branch of applied science predisposed in using and manipulating energy through an optical fiber. This clarification is needed to correct the oft used but context-wrong sentence. But for the sake of simplicity, we should continue using fiber optics as relevant to the device optical fiber.

How Fiber Optics is made with CVD?

So, how fiber optics is made? Fiber optics (optical fiber) is made through a series of chemical reactions. The first chemical process is a CVD (Chemical Vapor Deposition) where the preform ‘glass’ is the product of two gas substrates silicon tetrachloride (SiCl4) or germanium tetrachloride (GeCl4) mixed by precursor substance oxygen. Picture this; a hollow glass tube with ends injected with the reagents is slowly rotated horizontally over a lathe. As the mixture heats up, it allows chemical reaction to take place, and the tetrachloride reacts with oxygen releasing silicon or germanium to form silica or germania oxides which deposits and accumulates on the tube’s wall. After some time, a volume of the substance is accumulated until reaching a sufficient amount, forming the desired preform.

This resulting ‘preform’ glass is different from conventional glass in many ways, that it has several strictly regulated properties along the manufacturing guidelines. It is extremely pure, for instance, to meet refraction index* standard. It is even stated that your casual eye ‘looking through’ a mile thick of this ‘preform’ will still allow seeing the opposite end clearly.

There are three known methods for CVD, the Inside Vapor Deposition (as illustrated), Outside Vapor Deposition, and Vapor Axial Deposition. And regardless of the chemical deposition used, the preform is the byproduct by which glass fibers are drawn. The two reagent substances silicon tetrachloride (SiCl4) or germanium tetrachloride (GeCl4) is used in creating the preform.

Drawing Fibers from the Preform

However created, the preform ends up on a drawing tower device. This device is another furnace, but no chemical reaction takes place. What it does is melt the preform blank* starting from the tip. The exit for the melted glass is at the bottom, a precision hole where the liquid passes through, falling and cooling as it does, forming a continues, laser micrometer regulated diameter, and collects on a tractor spool.

*Refraction Index, in the optical fiber concept, is the phase velocity in which light can travel along the fiber

*preform material already checked for quality control.

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