Optical Fiber

04 Jan Optical Fiber

What is optical fiber? We are used to the concept of moving knowledge in numerous ways. A wire cable transports the sounds from our speech into a socket on the wall and is borne by another cable in the nearby telephone interchange, as we talk in one landline phone. Smart devices work in a particular way: they are transmitting and receiving information on unseen radio waves—a technology dubbed wireless because it does not use wires. Fiber optics is the third way. It transmits coded information into a light beam through a plastic or glass pipe. Originally designed to allow doctors see the human body inside endoscopes in the 1950s without first having to break it open.

The same technique was used by engineers in the 1960’s to relay telephone calls with the speed of light (usually 186,000 miles or 300,000 kilometers per second in vacuum, although the speed in a fiber optic cable is slower to around two thirds).

Technology of Optical Fiber

Photo: 144-core fiber optic cable cross section. Per fiber optics center consists of optically pure glass and is thinner than human hair.

A fiber optic cable consists of unbelievably thin glass or plastic fibers known as optical fibers or optical core or optical fiber strand; a single fiber optic cable may contain as little as two or three Optical Fiber core. Every core is less than ten times as wide as the human hair and can hold around 25,000 telephone call capacity, meaning that many millions of phone calls can easily be received by a whole fiber optic cable. The latest fiber record (as explained below) is 178 terabits per second, enough for 100 million Zoom sessions.

Fiber optical cables are used with the whole optical (light packet) technology to bring information / data between two locations. Suppose you had to transfer details across the streets with fiber optics from your machine to a relative’s home. You would link your PC to a laser that transforms electrical data from your PC into a series of light pulses. Then you can shoot down the fiber optic cable with the laser. The light beams will surface at the other end after going down the cable. Your friend will have to have a photoelectric cell to transform the light signals back into details that his or she machine would recognize. The whole unit, then, will be like a very neat, high-tech type of telephone that you can make of two cooked cans and a string length!

How Optical Fiber working

Photo: Fiber optic cables are too thin to bend and even take light in curved tracks.

Fiber optic cables are sufficiently fine to bend and even take in curved tracks light signals. Artwork: The total internal reflection assures that light rays flow into the interior of the fiber optic wire.

Light is streaming through a fiber optic cable that repeatedly mirrors the walls.  Much like a bobsleigh, any little photon (particle of light) bounces off the tubing. Now you might imagine a light beam to spill out of the sides in a transparent glass pipe. ((More technically, the cladding has a lower refractive index)

Fiber optic cable type

Light radiation modes in optical fibre modes for single and multi-mode stage index cables

Light pulses in so-called modes transmit optical fibers. It sounds mathematical, but it means different methods of travel: the way a light beam passes the fiber is just a mode. One mode is to travel right down the middle of the fiber. The fibers, in a flaccid angle, are also reconstructed.

Picture: Using single mode and multi-mode fibers, Light transported in various directions. See below, A typical single mode optical fiber cable within (not to scale). A rubber outer shell (around twice the thickness of the cladding) is over the thin core with some supporting fibers made of a durable material like an Aramid Yarn with a shielding external jacket at the outside. The latter is about ten times larger.

Single mode is the simplest type of optical fiber. It is very small with a diameter of roughly 5-10 microns (millionths a meter). Both signals pass right through the center without bouncing from the edges of a single mode fiber (yellow line in diagram). Cable TV, telephone signals and the Internet are typically filled with fiber in one fashion. Such cables can transmit data over 100 km (60 miles).

Multi-mode is another form of fiber optic cable. All fiber is nearly ten times greater than one in a single-mode cable in one multi-mode cable.

Via a multitude of various directions (yellow, green, blue and cyan lines), light rays will thus cross the heart — in several different ways. Multi-mode cables can relay data only for a comparatively short duration and are among other things used to link computer networks.

Still thicker fibers are used to diagnose the disease within the stomach, in a surgical instrument called a gastroscope (a form of endoscope). An optical cable composed of a variety of optical fibres, is a gastroscope.

An ocular and a lamp are situated at the end of the gastroscope. A part of the cord is lit by the light towards the abdomen of the patient. When the light enters the liver, the lens at the bottom of the cable reflects from the stomach walls. And it returns to the doctor’s eyepiece another portion of the wire. Related endoscopes may be used to view various areas of the body. There is also an industrial version of the instruments known as a fiberscope that can be used to display elements as inaccessible components of machinery in aircraft motors.

Photo: Fiber optic cables are thin enough to bend, taking the light signals inside in curved paths too.

Optical Fiber Applications

Shooting light down a pipe sounds like a fun trick in the physics, and maybe you don’t believe there will be many realistic uses for such a thing. However, just as energy can fuel various kinds of devices, light beams can offer a wide variety of information—to assist us in several respects. We can’t see how ordinary fiber optic cables are because the laser-powered beams flicker under our feet deep under the business floors and city streets. This is very invisible in the infrastructure used – networking for computers, television, medical scanning, and military devices (to name only four). 

Networks of computers

The keyway to transmit information over long distances are now fiber optic cables and they have three major benefits over old copper cables:

Less attenuation: (signal loss) Communication is about ten times more transmitted until it needs enhancement – simplifying and sustaining fiber networks.

No interference: There is no “crosstalk” between fibers, unlike copper cables, so information is more accurate with higher signal efficiency. Thus, there is no interference between copper cables.

a high capacity of bandwidth: as we have already seen, fiber optic cables are far more data compatible than same-diameter copper cables.

Thanks to the Internet, you are now reading this article. You have obviously selected a search engine such as Google that runs a worldwide network of giant data centers linked by massive fiber optic cables (and is now trying to roll out fast fiber connections to the rest of us). You have downloaded this website from my web site after you had clicked on a search engine connection, and my words have pushed you more fiber optic cables most of all. In reality, optical cables do almost all of the work any time you go to the Internet, if you use fast fiber-operated broadband.

Just the last part of your ride (the so called ‘last kilometer’ from the fiber-connected cabinet on your path to your house or apartment) includes old-fashioned wires for most fast broadband connections. The “likes” the “tweets” now carry on under the streets in a growing amount of rural areas and even deep under the seas that bound continents. These are surely fiber optic cables and copper communication cables.

If you portray the Internet (and the World Width Network on it) as a worldwide web of spiners, fiber optic cables are the strands which keep it together. Fiber optic cables account for 99 percent and are 99 percent of the entire traffic of the worldwide communication.

The quicker users can access the Internet, the better the online ability and capacity. The emergence of broadband Internet made the cloud computing revolution inevitable (where people store and process their data from a remote location using online resources rather than a home or company PC).

Similarly, it would be much more popular to do stuff like broadcast films online instead of viewing a broadcast TV or renting DVDs with constantly fiber broadband (typically 5-10 times faster than standard DSL broadband using ordinary telephone lines). We will track and watch even more facets of our lives online through the so-called Internet of Things with more fiber capacity and quicker connectivity.

However, the data that streams down fiber optic cables are not simply public Internet.

Computers have been connected by telephone lines or by copper Ethernet cables over long distances, but fiber cables are increasingly a favored networking form, as they are more inexpensive, stable, reliable and have far higher capabilities. It is entirely possible for a corporation to build its own network for fibers (if it can afford to do so) or to (more likely) lease bandwidth on private fiber networks, rather than connecting its offices to the public Internet. Many of the private data networks operate on what’s called dark fibers, which sounds a little catastrophic (optical fibers waiting to be lit up).

The Internet has been cleverly developed to ferry any kind of information for any sort of use. While once land lines carried the Internet, now telephone calls (and Skype) are carried on the Internet fiber optic. Where a complicated patch of copper cables and microwave communications between towns once switched over telephones, the bulk of long-term calls are now routed down fiber optic wires.

A massive volume of fiber was laid since the 1980s; figures differ greatly, but it is estimated that the worldwide number lies several hundred million miles (enough to cross the United States about a million times). It was estimated that up to 98 percent of the “dark fiber” in the middle of the 2000s was unused; currently, while much more fiber is in operation, the bulk of the networks only contain only one-3 and a half dark fiber.

Broadcasting

Radio or TV broadcasting arose from a relatively simplistic concept back at the turn of the twentieth century, which meant that it was theoretically very straightforward to fire antennas on people’s homes with the electric waves from a single transmitter (on the television station). Nowadays, when the radio is already in the air, we can still get our TV over fiber optic cables.

Initially used coaxial cables (Copper Cables with a metal shielding sheath, covered around them to avoid crosstalk interference), whose transmission only carried a few analog TV signals, Cable TV networks pioneered the transition from 1950’s. With growing numbers of connecting individuals and networks providing a broader range of platforms and programs, cable providers have noticed that they have to switch from coaxial cables to optical fibers and from analog to streaming.

Luckily, physicists already understood how this was possible; Charles Kao and his colleague George Hockham had mathematical work done as far back as 1966 proving how a single optical fiber cable could supply a sufficient number of TV channels with sufficient data (or several hundred thousand telephone calls). It was only a matter of time before cable television was identified, Kao was appropriately honored for his accomplishment with the 2009 Nobel Prize in Physics.

Besides having a much larger power, optical fibers are less interfered, meaning that they deliver increased signal efficiency (photo and sound); require less amplification so that they fly long distances and are more cost-effective. In future, broadband fiber might well be how most of us view TV, maybe through systems such as IPTV (Internet Protocol Television), which uses the normal Internet way to deliver data (‘packet switching’) to TV programs and movies on request.

Although the copper telephone wire is still the key information route into many of the homes of many people, a high-bandwidth digital cable containing all manner of information in future will be our key link to the globe.

Medicine

The first right use of Optical Fiber about a half century ago were surgical devices that could help physicians look in our bodies without opening them up. Gastroscopes are as important today (as they are called) as ever, but Optical Fiber also produce important new ways of medical scanning and diagnosis.

One of the most recent advances is a fiber lab and the introduction into the body of a patient of thin, hair-thin fiber optic cables with embedded sensors. Specifically, close to those in communication cables and thinner than those seen in gastroscopes, these kinds of fibers are comparatively chunky light guides. How do they work? How do they work? The doctor needs to examine light zaps from a lamp or laser around the body portion. The patient’s body changes its characteristics in a certain manner as the light whistles through the filament (perhaps changing only subtly light intensity or wavelength).

An instrument attached on the other end of the fiber may calculate any vital aspect of how the body functions by calculating the way the light shifts (using methods such as interferometry, blood pressure, cell pH, or involvement of medicines in the bloodstream. In other words, this type of fiber optic cable uses light instead of just using light to see inside the patient’s body.

Military

The Museum shows Improved Fiber optical Guided Missile (EFOG-M).

Photo: Frontline fiber optics. This modified Fiber Operating Missile is designed to show the gunner where he is while he is flying, with an infrared fiber optic camera in his nose. The portrait of the United States Army is kind.

It is easy to envision the attachment of internet users to giant fiber cable webs; it is much less clear that high-tech military powers around the world are connected in the same way.

Fiber optic cables are cheap, small, lightweight, high-speed, durable and highly protected for attack so as to have ideal communications between military bases and other facilities.  Other facilities are usually missile launch sites and radar tracking stations. Although the electric signals they are not sending, they do not emit electromagnetic radiation that the enemy will track. (including “jamming” assaults by the structural enemy).

Another difference compared to conventional cables made of bulky and costly copper metals is the comparatively light weight of cables. Both tanks, military aircraft and helicopters converted from metal to fiber optic cables steadily. Half of it is a question of cost savings and weight reduction. (Fiber optical cables weigh about 90% less than equivalent copper cables of the “twisted-pair”). However, it also increases durability, such as optical fibers being entirely resistant to lightning strikes, compared to the conventional aircraft cables. These have to be properly protected (insulated) in order to protect them.

The inventors of Optical fiber

There is no a single inventor of optical fibers. There are more than a single name and these names are listed below:

1840s: Daniel Colladon, Switzerland’s physicist (1802–1893), noticed that a water pipe could be lit up by light. Internal contemplation took the water to the light.

1870: John Tyndall (1820-1893) was an Irish astronomer who showed his own reflection in the Royal Society in London. In a jug of water he gleamed light. The lights switched around on the direction of water as he spilled some of the water out of the bottle. This concept of “bending light” in fiber optics is precisely what exists. Though Colladon is the real fiber optics patriarch, Tyndall earns the money also.

The 1930s: The two German students Heinrich Lamm and Walter Gerlach attempted the development of a gastroscope using light pipes — a method to see into a person’s abdomen.

Narinder Kapany (1926–). Harold Hopkins (1918–1994). In London, England, They were able to send a clear image down a light pipe made of thousands of glass fibers. Kapany is widely considered as the “father of fiber optics.” after writing several research articles.

1957: The first fiber optic equipment in the world was successfully employed by three American scientists, Lawrence Curtiss, Basil Hirschowitz and Wilbur Peters, at the U.S. Michigan.

1960s: US physicist Charles Kao, born in China from 1933–2018, and George Hockham from his colleague realized the use of impure glass in long range fiber optics. Kao proposed that a very pure glass fiber optic cable could transport phone signals over long distances. For this pioneering find, Kao was given the 2009 Nobel prize in physics.

1960s: Corning Glass Corporation engineers developed the first fiber optic cable to bear phone signals.

~1970: Donald Keck and Corning’s colleagues have been able to provide signals even better (with less loss), which are conducive to the production of initial low-loss fires.

1977: Long Beach was built with Artesia, California as the first fibre-optical telecommunications cable.

1988: The United States, France and the United Kingdom laid their first transatlantic fiber optic telecommunications cable, TAT8.

2020: Tele Geography reveals that at present there are about 406 submarine fiber optic cables reaching a total of 1,2 million km (carrying communications under global oceans) (0.7 million miles). This is an improvement of 378 cables in 2019, but it appears that the overall span is the same.