Fiber Optics

Fiber Optics is a sub-working field of optics. While optics is the field of light, fiber optics is concerned with the optical phenomenon in Glass Fibers only. Fiber means threads and when we called fiber optics it’s usually glass threads that can enable the light can pass through. All the physical phenomena and telecommunication matters include fiber optics. Today most of the internet is based on fiber optic cables. They are the descendants of the copper electrical cables. But if there are electrical cables already, why do we use fiber optic instead?

Previous standard telecommunication cables are made of copper or other conductor metals. These cables carry electrons (or most of the time called current) from one end to the other end. With help of other devices, these running current carries valuable data. Former telephone lines and then internet lines were made of these types of cables.

Then these cables get old. Novel technologies take place these old cables. Fiber optic technology comes into the game at that point. While the transferred data gets bigger, electric current-based cables fail to function. In 1990 total internet users are 2.6 million people while in 2016 this number multiplied by 1310 and gets to 3.406 billion people. So far you have noticed that the conventional electric cables cannot handle the data and are replaced by the new technology which is Fiber Optic.

Fiber Optic Cable Vs Copper Cable

Fiber Optic Cables can transmit greater data than copper cables. To be speaking exact this speed difference exceeds from 10 times to 1000 times. This capacity difference puts Fiber Optics forward. But it is not the whole case. Fiber Optics are better than copper cables in many ways. ( Also has some defects but it’s later on.) We emphasize one of them which is the carrying capacities. The other is costs. For the understanding of cost, let’s look at what is Fiber Optic Cables made of.

Fiber-Vs-Copper

How Fiber Optic Cables Made Off

The main component of Fiber Optic Cable is Optical Fiber. Optical Fibers are made off Glass or some similar materials. The purpose of this fiber is to carry light (photons). Hence the material should be transparent. Carried light is generated through laser devices. In addition to these, materials should be durable, flexible, cheap, and easy to produce. I guess you only questioned the flexibility. Glass is surprisingly flexible at 9 micrometers diameter. Then it should be viable. Optical fibers are cheap because humans have thousands of years of experience with glass. Both industrial and craftsmanship. Through this experience, fiber optics are produced. A chunk of glass material hung to the high places and through some process glass gets thinner and thinner. From the diameter of meters, it becomes 9 micrometers. They call Draw Towers to high places which they hang on.

Fiber Optic Cable does not consist of only the “core”. As you can guess, the glass part is called the Core. But the light is propagating through the core without any protection. Also light scatters in random directions. Light needs a “waveguide” and protected layers. For making a waveguide, the core is coated with some material. This coating is called “Cladding”. This material’s Refractive Index is lower than the core. It makes light propagate inside the core. Then some protecting layer is applied. It’s called “Coating”. For special uses, the cable can be coated with many different materials. Including UV protection and Radiation Protection. By these protections, Fiber Optic Cables can be used anywhere including underground transatlantic telecommunications.

Fiber-Optics

How Photons Travel Inside The Optical Fiber

Light (photon) travels inside the core as we know. It bounces fiber walls. The design of the fiber optic cables is unable to propagate outwards. Nevertheless, some of them propagate out of the cable. It is called Optical Loss. We will be going through optical loss in another heading.

The physical law that makes light bounce and stay inside the cable is Snell’s Law. Never going out while bouncing is a phenomenon called Total Internal Reflection.

snells law
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