Fiber Optics By Oscar Barragan What are Fiber

Fiber Optics By: Oscar Barragan

What are Fiber Optics? Fiber optics are the use of thin flexible fibers of glass or other transparent solids to transmit light signals, chiefly for telecommunications or for internal examination of the body. Fiber optics are long, thin strands of very pure glass about the diameter of a human hair. They are arranged in bundles called optical cables and used primarily to transmit light signals over long distances. • Core - Thin glass center of the fiber where the light travels. • Cladding - Outer optical material surrounding the core that reflects the light back into the core. • Buffer coating - Plastic coating that protects the fiber from damage and moisture. Hundreds or thousands of these optical fibers are arranged in bundles in optical cables. The bundles are protected by the cable's outer covering, called a jacket.

The History of Fiber Optics The history of fiber optics really began when the late 1790 s when the French Chappe brothers invented the first optical telegraph. Then Daniel Colladon proved that light could flow through water jets in the 1840 s. And in 1854 John tyndall proved that light could travel through a curved stream of water proving that light can be bent. The idea of fiber optics was always there but it was not until 1960 when lasers were invented that fiber optics became a reality. In 1961 a year after lasers were tested and approved they made a theoretical description of single mode fibers. But when making it the light loss became too great. They fixed this in 1970 by doping the silica glass with titanium. And in 1975 it was tested and two years later the first live telephone traffic through fiber optics occurred in California. And in the early 1980 s it revolutionized the telephone company's.

Fiber vs copper

Advantages of Fiber Optics • Less expensive - Several miles of optical cable can be made cheaper than equivalent lengths of copper wire. This saves your provider (cable TV, Internet) and you money. • Thinner - Optical fibers can be drawn to smaller diameters than copper wire. • Higher carrying capacity - Because optical fibers are thinner than copper wires, more fibers can be bundled into a given-diameter cable than copper wires. This allows more phone lines to go over the same cable or more channels to come through the cable into your cable TV box. • Less signal degradation - The loss of signal in optical fiber is less than in copper wire. • Light signals - Unlike electrical signals in copper wires, light signals from one fiber do not interfere with those of other fibers in the same cable. This means clearer phone conversations or TV reception. • Low power - Because signals in optical fibers degrade less, lower-power transmitters can be used instead of the high-voltage electrical transmitters needed for copper wires. Again, this saves your provider and you money. • Digital signals - Optical fibers are ideally suited for carrying digital information, which is especially useful in computer networks.

Physics of Fiber Optics Optical fibres are used to carry signals in the form of pulses of light over distances up to 50 km. They do this by Total Internal Reflection. That's why optical fibers can guide light for such long distances - because the walls of the fibre don't absorb any light at all as long as the angle of incidence is greater than the critical angle. Total Internal Reflection causes 100% reflection. In no other situation in nature does this occur, so it is unique and very useful as it is 100% efficient at transferring the light energy. There are two conditions necessary for Total Internal Reflection to occur: - The refractive index of the first medium is greater than the refractive index of the second medium (n 1>n 2) - The angle of incidence must be greater than the critical angle (i>c) When light hits the boundary between two substances it gets reflected and refracted. Light principally refracts at low angles of incidence, but as the angle of incidence increases the percentage of the light energy that reflects rather than refracts increases until the internal surface acts as a mirror. This is called TOTAL INTERNAL REFLECTION, because all of the incident light energy is reflected. The reflection then is even better than at a mirror's surface because 100% of the light energy is reflected by TIR whereas reflection at a mirror surface is never 100%.

Mathematical equations This angle is the largest angle of incidence at which light can enter the end of the fiber and be totally internally reflected inside the fiber. Angles of incidence larger than this angle will transmit through the sides of the fiber and not make it to the other end. The numerical aperture is a measure of the light-gathering power of the fiber. It has a maximum value of 1 (all the light remains trapped inside the fiber) and a minimum value of 0 (only light incident at an angle of 0 degrees on the end of the fiber remains trapped in the fiber). This characteristic measures the difference in time that different fiber modes take to reach the end of the fiber. The larger this time difference, the shorter the fiber has to be so that the information on this light doesn’t turn into junk.

The Design of Fiber Core and Cladding An optical fiber consists of two different types of highly pure, solid glass, composed to form the core and cladding. A protective acrylate coating (see Figure) then surrounds the cladding. In most cases, the protective coating is a dual layer composition. A protective coating is applied to the glass fiber as the final step in the manufacturing process. This coating protects the glass from dust and scratches that can affect fiber strength. This protective coating can be comprised of two layers: a soft inner layer that cushions the fiber and allows the coating to be stripped from the glass mechanically and a harder outer layer that protects the fiber during handling, particularly the cabling, installation, and termination processes.

Single Mode and Multimode Single Mode fiber optic cable has a small diametral core that allows only one mode of light to propagate. Because of this, the number of light reflections created as the light passes through the core decreases, lowering attenuation and creating the ability for the signal to travel further. This application is typically used in long distance, higher bandwidth runs by Telcos, CATV companies, and Colleges and Universities. Multimode fiber optic cable has a large diametral core that allows multiple modes of light to propagate. Because of this, the number of light reflections created as the light passes through the core increases, creating the ability for more data to pass through at a given time. Because of the high dispersion and attenuation rate with this type of fiber, the quality of the signal is reduced over long distances. This application is typically used for short distance, data and audio/video applications in LANs

Applications of Fiber Optics The applications for fiber optics are almost endless they are used in so many devices we use everyday in surgery and dentistry, mechanical inspections, lighting/decorations, and the automotive industry. But they revolutionized things like: Internet: Fiber optic cables transmit large amounts of data at very high speeds. This technology is therefore widely used in internet cables. As compared to copper wires, fiber optic cables are less bulky and carry more data. Television: These cables are ideal for transmitting signals for high definition televisions, because they have greater bandwidth and speed. Telephones: Calling telephones within or outside the country has never been so easy. With the use of fiber optic communication, you can connect faster and have clear conversations without any lag on either side. Computer Networking: Networking between computers in a single building or across nearby structures is made easier and faster with the use of fiber optic cables. Users can see a marked decrease in the time it takes to transfer files and information across networks.

Sample Questions Copper cables is better used for long distances. True or False Fiber optics cables are cheaper than Copper cables. True or False Fiber optics … a) transmit food b) transmit light signals c) transmit energy What part of the fiber optic cables carries the light a) Core b) Cladding c) Buffer d) Jacket

Bibliography Freudenrich, Craig C. "Fiber Optic → A Description of Fiber Optics. " DSL Reports. N. p. , 10 Mar. 2002. Web. 31 May 2017<http: //www. dslreports. com/forum/r 2721569 -A-description-of-Fiber-Optics> Ghatak, Ajoy K. , and K. Thyagarajan. Introduction to Fiber Optics. Cambridge: Cambridge U, 2004. Print. Dejony, Ted. "History of Fiber Optics. " Timbercon: Fiber Optic Cables. Timbercon, n. d. Web. 31 May 2017. "9 Uses of Fiber Optic Cables. " Do It Yourself 1997 -2017, 25 Mar. 2010. Web. 31 May 2017. <http: //www. doityourself. com/stry/9 -uses-of-fiber-optic-cables>. Fibre (Fiber) vs Copper as Fast As Possible. Dir. Techquickie. Perf. Techquickie. Youtube. com. Youtube, 23 Dec. 2014. Web. 31 May 2017. <https: //www. youtube. com/watch? v=_Bw 2 NFBDx. R 8&t=36 s>. "Fiber Optic Technology. " Springer. Reference (n. d. ): 1 -23. Corning. The International Engineering Consortium, 2014. Web. 31 May 2017. <http: //www. dsif. fee. unicamp. br/~moschim/cursos/ie 007/fibraoptica. pdf>. Hecht, Jeff. "An Introduction to Fiber Optics. " Understanding Fiber Optics 5 (2005): 1 -800. Print.